Why eggs make some people feel sick?

Some people remain fine eating the white egg but have a sensitivity to the egg yolk.

While some people have sensitivity eating white egg part but do not have any intolerance eating egg yolk. 

If someone is allergic to egg, they can neither eat its white nor yellow part as it will make them feel sick.

Some people are suffering from digestion problems and have sensitive stomachs. Eggs do not suit much to these people whenever they eat it alone. So, they prefer consuming eggs along with food containing fiber.

Eggs are very rich in protein. If you mix one protein-rich food with another high protein food, it may raise your stomach problems. Therefore, you must know what type of food to be combined with eggs to maintain an adequate protein balanced diet.

Eggs do not suit some people as they cause abdominal pain or diarrhea. The white part of the egg can boost the release of histamine, which is a compound in immune response from master cells. (See Why Green tea makes me feel sick?)

If you eat eggs on an empty stomach, it may create certain types of stomach disturbances. Hence, it is preferred by some people always to eat something before they eat eggs. 

Some people's stomach is not accustomed to egg protein as their immune system is triggered when they eat eggs. (See How your mind can make you sick?)