What is the historical evidence of people gagging and vomiting while being exorcised?
I truly do not believe that what you are asking about is a recent phenomenon. I equally believe that you will not find any external evidence of a historical nature on this subject.
This is not something that is typically written about.
If fact, Catholic exorcists are required not to name the victims of demonic possession. So Catholic exorcists generally would only talk about such things in the third person. People has the right to privacy and how would such information be compare to their reputation as good standing Christians.
I am not a fan of believing exorcisms published on YouTube, as in reality exorcisms are not for the faint hearted!
The De Exorcizandis Obsessis a Daemoni of the Rituale Romanum of Pope Pius XI requires exorcists to vomit any cursed object that is within the victim of demonic possession.
He shall, moreover, command the devil to tell whether he is detained in that body by necromancy, by evil signs or amulets; and if the one possessed has taken the latter by mouth, he should be made to vomit if he has them concealed on his person, he should expose them; When discovered they must be burned. - De Exorcizandis Obsessis a Daemoni
When The Evil takes possession of someone and they seek the aid an exorcist, the proof of possession must be fully ascertained before he can be given permission from the bishop to perform the exorcism. There are many things that must come into play here: doctors in various fields of medicine, etc...to aid the exorcist. Vomiting is just one of the many signs of possession and at times in great volume.
According to the Vatican guidelines issued in 1999, “the person who claims to be possessed must be evaluated by doctors to rule out a mental or physical illness.” Most reported cases do not require an exorcism because twentieth-century Catholic officials regard genuine demonic possession as an extremely rare phenomenon that is easily confounded with natural mental disturbances. Many times a person just needs spiritual or medical help, especially if drugs or other addictions are present. After the need of the person has been determined then the appropriate help will be met. In the circumstance of spiritual help, prayers may be offered, or the laying on of hands or a counseling session may be prescribed. The exorcist might not perform an exorcism if he doesn't know the person.
Signs of demonic invasion vary depending on the type of demon and its purpose, including:
1.Loss or lack of appetite
2.Cutting, scratching, and biting of skin
3.A cold feeling in the room
4.Unnatural bodily postures and change in the person's face and body
5.The possessed losing control of their normal personality and entering into a frenzy or rage, and/or attacking others
6.Change in the person's voice
7.Supernatural physical strength not subject to the person's build or age
8.Speaking or understanding another language which they had never learned before
9.Knowledge of things that are distant or hidden
10.Prediction of future events (sometimes through dreams)
11.Levitation and moving of objects/things
12.Expelling of objects/things
13.Intense hatred and violent reaction toward all religious objects or items
14.Antipathy towards entering a church, speaking Jesus' name or hearing scripture.
It is not hard to imagine that the Devil tries his upmost to remain hidden, but once he has been discovered through an exorcism he will try his hardest not to be expelled. If he has to spit, vomit or worse at the exorcist he will. I had a priest exorcist tell me more than once: "You can not imagine how many times I have been spit in the face!"
Exorcists are required to be very prudent when asking questions about how a person became possessed:
15 But necessary questions, are for example; about the number and name of the spirits inhabiting the patient, about the time when they entered into him, the cause thereof, and the like. - De Exorcizandis Obsessis a Daemoni
Fr. Gabiele Amorth in his book An Exorcist Tells His Story (Pages 137 -139) has this to add to questioning the Demon, vomit and liberation:
Norm number 20 of the Ritual suggests asking the Demon the cause of his presence, particularly whether it is due to something the individual ate or drank. If this is the case, the exorcist must command the person to vomit. If instead the curse is due to some foreign object, the exorcist must ask to be shown where the object is hidden, find it and burn it. - De Exorcizandis Obsessis a Daemoni
So if the case is do to something the victim of
possession has eaten the exorcist must demand the demon to puke it up so he can destroy it by fire!
Scene from the movie: The Exorcist.
As I mentioned above this whole subject matter is not something that is typically written about. For example, historical records, if they exist at all, on dry-heaving is quite similar to the act of vomiting in that physical muscles used are the same. Just because a person has dry-heaves does not mean he is going through the actions comparable to vomiting. Perhaps the victim has to ammunition in his stomach to expell. This leads me to recall that some call the act of vomiting, an exorcism (in slang usage).
Having first hand knowledge of what goes on in the real McCoy exorcisms with Catholic exorcists, I can assure you that the only person an exorcist is obliged to explain things that transpired during an exorcism is his bishop and no one else. No wonder that there is a lack of documentation on the physical happenings that occur during exorcisms. For this reason, I seriously doubt published stories of exorcism on YouTube. Besides that, those who aid an exorcist are not to speak about the happenings except in generalities. Besides the victim of an exorcism has the right to privacy in this matter. Others have no right to know the ins and outs of a particular exorcism, except in extraordinary circumstances.
Of all the phenomena that the OP has mentioned, I can assure you that those ones listed are only the tip of the iceberg. To start understanding the in and outs of this subject matter one has to have read the lives of those who dwelt on the front lines for many years as exorcists and not simply wanting to have a bunch of historical facts to digest.
One exorcist friend has told me that he can not even come close to counting how many times he has been spit on by a possessed person. Another one has had the victim of an exorcism walk on the ceiling, in order to rattle everyone’s nerves. As for things flying though the air, I am not even going to go there.
Anyone one aiding an exorcism, I have one solid recommendation: be in the state of grace!