I haven't heard of the pencil technique. I've heard that it helps a lot of people. Yes I think Paxil will help some people. The thing is that everyone responds differently to these medications. So Paxil may help one Prozac help another and so on.
Some people react strangely to medications.
No, you can start treatment using breathing methods, and the Paxil will not interfere. When you are confident that you can control panic and feel better, then you can ask you doctor to help you off the Paxil, or any other of the anti-depressants. I used to always get depressed around Christmas. Shorter days seem to affect a lot of folks. I was diagnosed with hypoglycemia years ago but has seemed to have gone away.