Hi Sir This Is Shyam, If I Eat Any Foods

Hi sir this is shyam, if i eat any foods like wheat,milk and milk products, soya chunks,meat etc.. My face skin is getting dry and itching even im feeling feverish aftet eating ,i have this problem from almost 5years i have consulted many doctors but no use.. Is this food allergy? I have done food allergy test but in test there is no positive reactions found everything is normal... How can i cure it... Please tell me sir..