It is tough especially with all of your allergies,but oh so worth it. I would suggest making a list of all of the meals you can have and know how to make, maybe even search the web for some more recipes. Type up a menu plan for a month, including your rotation. When you make these foods make enough to freeze several one serving portions and label them well. You will have to clean out your freezer if you only have a small one in your fridge. (If you are like me there was a lot of stuff in there that I couldn't eat) Give or throw out that food, it is hard, but you can't eat it anyway. I find it is so much easier when I have meals prepared ahead in the freezer, then on the nights I am prepared and feeling like cooking I can and the other nights I just grab out of the freezer and warm up.
As far as the grocery store goes, I find I pretty much just walk the outside perimeter of the store. I have learned to not feel bad about that, I don't crave any of that processed stuff anymore at all.
If I were you I wouldn't even worry about the testing, just start eating the things you know you can have, if you are allergic to gluten, then I would cut all grains out of your diet. I would also check your supplements and make sure they are also grain free, if they are not, you may want to contact Dr. O's office and purchase your supplements through him. (that could be causing your relapse feeling)
I hope this helps, don't give up! We all go through trials and tribulations, think of this group as your gluten free support group!