I have three food allergies that just manifested @age 35. now im ill all the time. Could these allergies be a symptom of another disease? Why so late?

? intolerance. vs a true allergy to whatever foods that cause the problem, yes food allergy can occur late, although uncommon, you need to see an allergist/ immunologist and may be a gastro-enterlogist and a dietician, but ask your primary doctor first for initial evaluation, best wishes.