Here's an update on Poltergeist's condition:
The cytology found that he had an abnormal number of macrophages and heterophils, suggesting that he has some type of infection (either fungal or bacterial). If it's a fungal infection, there is no treatment that is plausible, so, I'm putting him on bacterial medication for three weeks that will hopefully work. Unfortunately, it is too much money to figure out what exact type of bacteria/fungus he's infected with and to treat him for anything else. I have my fingers crossed that the medication will work.
Thanks again for helping me out.