You haven't listed any symptoms, and psychologists don't do meds, psychiatrists do, so this is confusing. More information will help. And this cold turkey stuff, why put yourself through that? Taper, taper, taper. By the way, Paxil doesn't require increased dosages to work, though it can stop working at some point.
Fentanyl is an opioid-agonist and therefore you WILL experience withdrawal problems if you go cold turkey with this one. Are you trying to quit both meds at the same time or just Paxil?(sorry, I didn't get it).
There might be some subtle interaction between the two drugs that somehow makes it more difficult to quit Paxil this time.
Listen to Paxiled. Taper.
Good luck,
Nora