Eczema Treatment Care

I went to an allergist a couple of days ago because I think I have an allergy to wheat. I have a continual itchy rash on my leg that spreads every time I eat wheat. Well she did a patch test and the test showed negative. She checked the rash and said it looks like contact dermatitis. Ok , I’ll buy that. So she gave me cortizone cream and lotions and I am using them and the rash is starting to clear up. The problem is I ate some wheat for lunch yesterday and the same rash an hour later now popped up on my inner arm. Can this happen? I have done every thing do solve the contact dermatitis (she says from the detergents and soaps). I’ve stopped using them. So why is this rash popping up on my inner arm now. I think I still have an allergy to wheat. Can this be?
OOPS she gave me a skin prick test not a patch test. Sorry.

when i was pregnant with my first child 18 months ago i developed atopic eczema all over my body, i tried every cream on the shelves and antihistamines along with steriod cream
it looked like i had been burned by a chip pan and felt like hell i couldnt bare clothes on my skin and soon i couldnt sleep or go out much and developed depression.
now i still suffer with eczema but nothing like i did and its very controllable!
what i wanted to now is if any one has had anything like this and if its likely to happen again if i become pregnant again??
any prevention ideas would be appreciated to ( besides the idea of not getting pregnant again)