Why am I breaking out in painful hives when I touch/eat anything?

[Felinecatapult]

I have always had really sensitive skin and I've developed reactions to most medications, but I had the flu about two weeks ago, which seemed to clear up and since then I've been covered in extremely painful hives as well as sores in my mouth and throat. I've tried everything (benadryl, other antihistamines, hydrocortisone, even neosporin on really bad areas) and tried to avoid almost every possible allergen I can think of. If I eat anything, even my "safe foods", the hives seem to worsen. Even wearing loose fitting clothes is excruciating and inflames the hives more until the scab. Almost everything that touches me, even taking a shower burns and hurts way more than hives have ever felt to me before.. Besides the sensitivity, my head has been aching and sort of foggy, like i can't think straight and I've had the same sore throat, achy muscles, and fatigue (which isn't uncommon for me). I don't know what to do, any ideas on what it may be?
Sorry, I forgot on major detail; I've had diarrhea since the flu started and it's extremely uncomfortable