as your ages, your body's immunity changes, take type II diabetes for example,
look at the animal kingdom, think if a squirrel had nut allergy? how about a tuna with shrimp allergy? or a cow who can't tolerate gluten.
Eat veges fruits of different colors, same goes for nuts and berries.
try an alkaline diet for few months and see if that helps, you have to think outside the take 2 pills and call me in the morning approach.