Hello,
For about a few months now, every time I lay down on my back to go to sleep at night , I get a pulsating, pressure like feeling on my left rib. I am worried that it may, G-d forbid , be a tumor. Does a tumor pulsate when only lying down on back? When I stand or walk or sit I do not feel it. I am a little gassy. What could this be please help. Thank you.