This may or may no be useful for you and I have cut ties with that world so I can’t find any link to it, but here goes.
One of the very few “cures” for schizophrenia is a form of exorcism done by hypnosis.
It isn’t very well known or widely practiced. If you find information on it, you will be able to figure out the advantages to this approach.
Everything in the hypnosis world is regulated and checking someone’s track record and confirming their competence is easy. Should be much cheaper too.
But if you jump on it, be sure to research as much as possible. Ask them for their usernames in forums (very common in hypnosis) and check how they talk about their previous cases there too.
Do enough intel gathering and you’ll know very clearly who you’re dealing with. But check the internet too, not just some listing and good reviews or recommendations from other hypnotists. That’s more a form of relationship building that a critique on their competence.
Apologies I can’t give you any name, but since it isn’t that common, you either find them or you don’t (they may have moved on from doing this).
Also I mention this cause it involves (imho) real exorcism. Not saying you have schizophrenia, but simply that this approach may work for demonic attacks of different kinds.
On the other hand, it may be a light form of it, and after what you have already experienced, it may not seem that powerful. Afaik they don’t use that much latin stuff in these interventions. They are also purely christian based, as they banish any angel that isn’t of Christ (these demons are/pose as fallen angels).
Have you checked how this thing reacts to Holy Light? I remember a few fields with it. If it reacts negatively to it, maybe Holy Paladin or smth similar (that generates Holy Light constantly) could be harmful enough to keep it at bay and it could eventually decide to leave.
Worth checking with anyone on the forum that can send Holy Light to you.