I've been having this problem for the past few days now. I don't usually have this problem, but it was even worse yesterday. The day before yesterday, I had this huge beetroot which I microwaved for perhaps a little too long (it became soft). I know that what you digest has a direct impact on your digestive system. The next day I made the stupidest decision I could have made, which was to eat almost nothing but oils and prunes. Yesterday I had a sweet potato with a ton of olive oil, a bowl of dried pitted prunes, and a bowl of oatmeal with a ton of crushed walnuts. My stomach was not happy. I guess the bacteria in my gut is off balance or something, your farts are actually a good indicator of your digestive health, apparently.