What Do Cramps In The Lower Abdomen And Back Indicate?

A few weeks ago, I had sudden onset of lower abdomen and lower back cramping, resulting in diarrhea. This occurred about three times, all sudden onset. The same thing happened again in a few days. Time rocked on and I began to have chest pressure pain and discomfort. The hospital admitted me for heart tests. I failed the Nuclear Stress Test and this has to have a heart cath. It only showed small arteries. I was discharged and if I eat solid food, within an hour and a half, the lower stomach and lower back pain hits again, and numerous diarherra trips. This was after eating a Wendy” hamburger. After eating a bowl of soup, I was nauseous. After a bowl of cereal, I was in tremendous chest pain from heartburn. I have a significant history of acid reflux, but it has never made me have diarherra. I’m leaning toward my gallbladder, an US showed it to be normal; however, they haven’t checked my gallbladder function yet. Any suggestions? Thanks