I have been training for my 2nd half marathon and unlike my first half where I was training early in the morning, I am now training after work between 4-5 pm. I try not to eat anything after 2pm as to not upset my stomach or get cramps and I have found that my stomach has been really funny on my runs, almost like gassy with some stomach pains. I am very good about not eating anything that is upsetting and I try to drink a lot of water throughout the day. It's really weird and getting annoying. Does this happen to anyone else? Any advice?