hello i can understand your concern mam the description you have given about your problem clearly indicates that you have developed a condition called as PARAUMBLICAL HERNIA---- (1) actually the muscles around naval ( belly button ) are little weak in comparision to the other muscles of the body (2) what actually happens is that during pregnancy the abdominal muscles are streched due to the ingrowing fetus in the uterus and as the pregnancy advances these muscles around belly button are streched more and more (3) thats why doctors advice some exerises to strengthen the abdominal muscles after delivery (4) it seems either your doctor didnt advice or else you didnt do the adviced exercises after delivery (5) if the muscles get to weak a times comes when the inner contents like a part of the intestine or mesentry ( outer covering of intestines ) bulges out of the weakened part of the muscle and is felt like a little lump ( as in your case ) and this is known as paraumblical hernia in medical terms (6) this condition is more common in women than men because of the obvious reasons which i have explained above (7) the treatment of this condition is surgery in which the bulged part is pushed back inside and the torn muscle region is stiched (8) although this surgery is usually performed under general anaesthesia but you plz dont need to get tense as its not a major surgery...if performed at the early stage it is a minor surgery without any risk of grave complication (9) so i would strongly suggest you not to waste any time and visit a good general surgeon who would clinically evaluate the extent of hernia and will do the needfull i hope the detailed explanation i have provided would help you regards