I have pain and stomach aches after eating even one cooked egg. What could be the problem? Allergies to egg?

Food sensitivity. You likely have a food sensitivity to eggs. This is an igg reaction, rather than true allergy to eggs, which is ige antibody reaction. Igg reactions can cause any symptom. Try avoiding eggs for 6 wks, then eat an egg to see if you have reaction. If you don't, try eating eggs no more than twice a week. If you do have reaction, avoid eggs another 6 wks, then try eating again. Repeat as needed.