Hey I had lower left abdominal pain for several months and I had an appointment with my doctor he had an ultrasound test and found nothing like kidney stones and said it might be due to musculoskeletal pain or groin related injury as I play football a lot. I was getting better but now all of a sudden I feel stomach burn at night when I lay down and have also developed mouth ulcers, both started almost the same day. Is it sometimes serious and if not what is it?