My son has abdominal pain and an enlarged spleen. He has had blood work and shows no sign of mono. He has had a problem for years with head aches and swelling of the legs and now has excessive sweating from right arm pit that is not the same as the left arm pit. Ultra sound showed the enlarged spleen but the abdominal pain is on left side just below the belt line. What specialist should we ask for to find the underlying problem. The abdominal pain has been ongoing for about two months now. Sitting and laying down are uncomfortable.