Ugh, sorry the titration process has been so hard and slow. It could be the paxil. Some blame all that happens after taking it on paxil withdrawal so it is hard to tell but it could be. What does your doctor say?
If that's your only problem, consider this a blessing. This drug is the hardest of them all to stop taking, and you're doing just great. I don't know of joint pain being caused by withdrawal -- the fact is, it's more likely to have it caused by taking antidepressants than not taking them, it's a very common side effect. Something to try is to take a healthy dose of fish oil every day, many say it helps a lot with withdrawing, and you might try supplementing with magnesium before you go to bed to see if it helps with the pain. Don't know your age or how much you exercise or anything like that. What would be more of a withdrawal symptom is if you already had the pain and it got a lot worse upon stopping a med, but when you play with the neurotransmitters in your brain you are playing with everything. One of the things serotonin does in the body is relax the muscles and nerves (along with other things), so when you play with it you can get pain. But it could just be from exertion or arthritis, so who knows? I always say, if something wasn't bothering you at all and then you either started a med or stopped a med and you got the problem for the first time, it's a likely cause of it.