Intussusception. On 4 years old baby.

Hello..what is this intussusception??what are the causes,symptoms, treatments??how is this effect on 4 years old baby.. I just gone through an article which says If your child is under age 4 and has stomach pain that causes him to double over one minute and be fine the next, it could be a sign of intussusception, a serious disorder usually affecting young kids where one part of the intestine slides into the other. The pain shows up in 20- to 60-minute increments and can be accompanied by vomiting, fever, blood in the stool, or bowel movements that have a telltale "currant jelly" appearance. "Call your doctor if your child only has severe pain," says Dr. Levine. "If there's crampiness plus signs in the stool, head straight to the hospital." My son is having stomach pain which lasts just for a min and it goes in it's own from past 2 months..I already consulted dr and have used medication