I saw your post, and prayed for your request, but was convicted to write you this as well. I too went through a full body rash about 2 years ago, which changed my life drastically for the worst and then drastically for the better. I learned A LOT about what was at the root of the problem because nothing was responding to all that I applied and I had a background in skin care so I was especially frustrated.
Please start an IMMEDIATE FAST, the best you can on nothing more than ORGANIC LIQUID CHICKEN BROTH with green beans and tumeric. Drink whenever you are hungry, no limits. Cut out all tomatoes, potatoes, peppers and eggplant (the night shade vegetable), NO eggs, dairy, sugar, alcohola and most importantly BREAD for the first 30-90 days if you are unable to fast. If you are itchy as well, go to the health food store and purchase wintergreen ORGANIC only essential oils, take himilayan salt baths in tepid water and read JOB. I read 3 times during that period and after 44 days of the above, my rash of 1 year was gone every where but my thumb, which is when I received a divine intervention after pray from a co worker who told me to get a colonoscopy. That is an entire other story, but since then the rash has not returened.
If the rash still doesn't go away, PLEASE get a colonoscopy at your earliest convenience to rule out that, if it doesn't go away after your diet change. I will continue to pray for you.