You can begin to decrease the Paxil and start increasing the new medication as long as they are compatible, which most other ssri types will be. The other way is to go off the paxil over a three week period of gradual decline, or at least get to the lowest dose before symptoms, then start with the new medication.
Or you can do your own research and wean of the drug very slow than three weeks. I fyou do it this fat let me warn you, be prepared for hell, becuse that is exactly what you will go through. Seems like you've already experineced a bit of this. You see paxil and all the other ssri's and antidepresant are very addictive, even though many doctors say the opposite. People do not know the hell you go through while trying to get off these drugs unless they been through this. I myself speak from personal experience. You cannot stop this drug so fast, I tried this and oh my goodness, I experinced. all the things you mentioned. Many doctors, not all of them, will tell you that they have never heard of anyone going through what you are going through, that they are just your old symptoms coming back, that you need to stay on some of type ssri or antidepressant for the rest of your life, just like a diabetic needs to take their medication to stay well. They will also try to tell you that you have some kind of chemical imabalance. Tell them run a test to prove this. There is no such test. The chemical imbalance thing is just a theory and they have no way to prove it. Please seek other alternative help. These drugs are dangerous and very addictive. GO to paxilprogress.org. It really helped me when I thought all was lost. They are a nonprofit site geared to help educate the public about the dangers of these drugs and how to help people get off them.