I had the exact same symptoms for a year and a half. I had an eye test done at a Hollistic store. It turned out to be candida, which produces it's own gases. I was filled with it! My stomach was so loud 24/7.. So embarrassing. I couldn't escape it. Def sounded like something was growing in me! And it was! This monster fungus called candida! Also, I was vegetarian so long my colon shrank ( well became narrow, like diverticulitis?).. It's suppose to be about 3 inches in diameter, mine was only 1 inch. This made my belly have to work over time . It was making noises as well! I added fiber to my diet (like massive amounts of fiber) it helped a lot! What happens is the food gets trapped and ferments. It doesn't digest fully. This can created a lining in the stomach as well, from the Undigested food. If you're switching from constipation to loose stools this can be a symptom. It gets trapped til it finally blows! Lol the main problem was my candida tho. Thanks to synthetic birth control use!