New with Anxiety due to Fear of Flying

So last year I'd gone on 7 trips for work all over the country. However, during my last flight home from Atlanta, I suddenly got horribly claustrophobic, which had never happened to me before. I also had the sense that I couldn't get enough air and started to freak out a bit. I was able to calm myself down, but the effects made me nervous. Then I was supposed to go on another flight to DC after the weekend. The whole time I couldn't relax. I had no appetite, couldn't sleep and was a basket case. As it turned out, I ended up not even going on my trip because my anxiety was so severe. I was prescribed Xanax, but that only made me pass out and when I woke I was just as anxious as ever. Even after I knew that I wasn't flying anymore, it took me a good 3 days to finally calm down and get back to normal.

Since then I've not had to do anymore flying and was fine. That is until last Wednesday, when I got an email stating that my team would be having a meeting at the end of summer, which meant travel. That night I began to shut down, no appetite, didn't want to talk, nervous, and couldn't sleep. My wife even knew something was wrong and mentioned it. So I told her about the email. Well I was like that all weekend long. I know it is anticipation anxiety, but this time I can't seem to shake it and it has even started leading to slight depression, like thoughts of why am I so messed up and what is it all for??? Stuff like that, which is SO not like me!

So Monday I went to my GP Dr and told him of my situation. He diagnosed me with GAD and prescribed me Paxil. I'm now on day 2 (taking 10mg the first week), but my guts are in a continual state of rumble and churning. Oh ya, and I have IBS-D too. So can anyone tell me whether the churning is just a side-effect and if it will subside after the 2-4 weeks??? Because the churning is making my IBS anxiety monster flair up too, which I had under control until taking this stuff. I'm really tempted to just stop taking it all together. So any input would be highly appreciated!

Thanks!