I Started Itching About 2 Months Ago On My Right

I started itching about 2 months ago on my right thigh. Now everywhere I touch on my skin a bump that looks like a hive comes up, it gets itchy, red and hot. Now it happens everywhere on my body including my gums and under my tongue. when I eat they become uncomfortable and inflamed. I have gained about 15 pounds in 2 weeks from water retention and my lymph nodes are swollen. I was on antibiotics which was a zpack which did not help. I have been on anthistamines for 2 months now with little relief. My Dr has ran several blood test and he said everything is normal. Any suggestions?