People are going to have very strong opinions about this and I am sure my comments will evoke the wrath of many members.
Personally, I believe that sometimes when people see 'spirits' they are not really spirit and are hallucinations, as mental illness is a genuine thing and can be caused by natural means. If your medication is stopping these spirits, perhaps you were suffering from halluicinations.
Saying this, seeing spirits is generally not a reason I would go to see a psychiatrist for....I also do not agree with medication which effects the brain.
You may be seeing spirits, you may be suffering from hallucinations, your psychiatrist may actually care, or he may just be giving you pills and getting paid for fobbing you off.
This is a controversial topic, and whilst I feel strongly, must for the sake of you possibly suffering mental illness, state that an advice given to you here, must not effect the diagnosis of a doctor, unless you can competently ensure your health will not be damaged in exploring an alternative to your predicament.
I would see a psychotherpaist/clinical psychologist, if you ask around you will find one who is spiritual and does believe in spirits who will be better equiped to deal with you. It is is better to find the correct therapist for you.
Quite a few clinical psychologists and psychotherapists actually practice magick, I can think of at least 4 who are in print, and I am sure there are a lot more out there not in print.
Of course, all is opinion, I am not mental health expert.