I have been right where you are. I've had panic/anxiety and agoraphobia for 17 years on and off. I was doing really well a few months ago, able to go where I wanted as long as I was with someone, and functioning very well. Now I'm in the midst of a pretty intense setback and back to avoiding going out very much. I've had stomach issues for the first time with this setback and admit that it has really scared me, but nothing to the extent of what you are dealing with, mine are strictly panic related, but I still understand the fear of leaving home as to not get stomach pain. I've taken xanax for years, and yes the tired feeling does wear off eventually. You have to keep in mind that your anxiety and physical ailments may also be causing you to be overly tired as well, but the xanax can make you very sleepy. I know that right now what you are going through is hellish, I'm there too, but I also know that this will get better if you get the right help. I've found a new therapist who comes to my home once a week, and there is progress there already. I don't take any other meds besides the xanax, and typically that is all I need to get by, although I still have days, especially mornings that are really, really hard. The anxiety can get quite intense, but I take the xanax as needed to get some relief until I can get my thoughts in order and deal with it through the tools I've learned. I know that it's hard to believe that panic/anxiety can make you feel physically sick, but it does. I deal with that alot, it comes and goes though. Trust me, you are not going crazy! I have those thoughts all the time, and in 17 years it's never happened, so I'm betting that it won't now...plus I've always heard that people who go crazy don't know and don't care that they are, so the very fact that you have a fear of it means you are okay, it's just scary thoughts getting control...try not to be afraid of thoughts, they can't hurt you!
I just want you to know that I'm here if you need some support. Our stories sound pretty similar, and maybe we could help each other through the rough spots. I'd be willing to give you my e-mail address if you'd like.
Let me know how you are doing.