Not sure, babe. I think you need to keep bugging your mom about that doctor's appointment, and if she won't listen, just call up the office and go on your own. Start with your GP if you have one.

Tumors don't generally thump, hun. Only hearts do that. Sometimes if you're anxious or your blood pressure is up, you can feel that thumping in your diaphraghm, which is down toward the bottom of your rib cage. "Rebound" heart-thumping (thumping you can feel in other areas than directly where your heart is) is more noticeable in the slender individuals like yourself. The large arteries leading away from the heart like the coronary artery and the aorta, which runs down your chest, also pulse with the heartbeat. You may be feeling that.