Could be a combination of the two. Wellbutrin is a pure antidepressant and can be stimulating, so isn't usually used if anxiety is a major problem (though it might be if the anxiety flows from depression). It is often used along with an ssri to deal with sexual problems caused by ssris. So you're describing classic Paxil withdrawal symptoms, but you could also be suffering side effects from a more stimulating med.
Sounds like it's mostly the withdrawal from the Paxil. Going on and coming off Paxil are always really horrible. Symptoms will subside once your Seretonin starts firing normally again.
You may want to start taking 5HTP to help with the withdrawal. You can buy this product at any drugstore or even walmart. It really does work to increase seretonin.
5-Hydroxytryptophan (5-HTP; Oxitriptan) is a naturally occurring amino acid, a precursor to the neurotransmitter serotonin and an intermediate in tryptophan metabolism. It is marketed in the United States and other countries as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid.
I have been on paxil 20 mg a day for last year and it really has helped my General Anxiety. Because of low libido and some weight gain though, I'm tapering off the paxil and starting 150 wellbutrin xl in the morning every day. I'm also supplementing with 5HTP until my seretonin goes back to normal. I think I will eventually have tyhe Doc up the welbutrin, but will see how the 150 does.
Good Luck!