Why is it everytime I drink milk I feel sick?

Lactose intolerance . Lactose intolerance means the body cannot easily digest lactose, a type of natural sugar found in milk and dairy products. This is not the same thing as a food allergy to milk.
Lactose? If this occurs after you eat milk or milk products you may have lactose intolerance. If only after milk you could have allergy or just a food intolerance.