I have had this constant fluttering in my upper stomach... maybe it is my sphincter. First time it lasted for a couple of months then magically went away for a month, now it's back. I do have GERD and take Protonix for it but the fluttering does not seem to go away. At first I thought it was my heart palpitating. Had stress tests, my dr. monitored my heart for 24 hours and my heart seems to be OK. It feels like a "rumbling" feeling behind my ribcage. It seems to get worse AFTER I eat and goes away completely after I have a cocktail. This fluttering hasn't diminished my appetite nor have I gained or lost weight. But it seems that I am swallowing air because I have been constantly burping. Is it a faulty sphincter that I have?. AND why did it go away for a month or so? I was taking ASACOL for a mild colitis problem that I had. The day I quit taking it, my problem went away. Lately I started taking Centrum Silver religiously one a day. After a week this happened again. WHAT IS THIS?