 [ Symptoms ] i have a lump under my lower left rib that sometimes causes pain what is it [ Disease ] most helpful answer i am sorry to hear you are experiencing this it sounds quite unpleasant unfortunately it is impossible to answer your question in a forum like this because diagnosing the problem requires a physical examination i suggest you consult your primary healthcare provider for an exam that said the situation does not sound dire a lump in the area you describe would probably be a nodule in the skin such as a fatty cyst of course if you are talking about a lump on the ribcage near breast tissue then this would be a concern but i am reading your question as a lump underneath the bottom of your ribcage on the left side at any rate a trip to the doctor is in order to get some answers wishing you well