Somach Discomfort that Subsides with Food and Activity

I have been having an issue with stomach discomfort for quite some time now. I can only really describe the problem as a kind of churning or bloating with a lot of gas build up. It seems that the issue will subside with food; I have often mistaken the problem for hunger. I have to eat several times throughout the day to keep the discomfort at bay. I've also noticed that the issue seems to arise when I am sitting upright for long periods of time and not when I am laying down or standing. I am a twenty-two year old male student and it can be very distracting since i am required to sit for relatively long durations. I have also noticed a dull pulling pain on the back of my belly button that complements the stomach discomfort. Any advice would be greatly appreciated.