Big rash appeared on1area. That disease?

It's almost been a year, on the 1st when I eat my arms feel itchy when I scratch it, big, large rashes appeared. 1st I thought it was allergy from fishy or ramish something like that because I frequency eating eggs and chicken. I always put petroleum jelly to make wounds dry (I got wounds by scratch ing because it's so so itchy that I cannot resist) it only apperede on my left arm about 2 inch before elbow down to before may wrists... Continuesly putting petroleum it's gone for I don't know reason.. About 2-3months I appeared again to my right arm about same area range. I stop eating fishy or ramish foods, I start eating veges and meat a lot, I still continue putting petroleum jelly to make it dry.. Weeks past and it gone again. I'm still continue the process of eating veges and meat. On the 3rd times its itchy part appeared on my right thigh when I simple scratch it not so hard.. Big/large rash appeared again so fast and it spread to my left thigh then to knee both, is that disease?