Idk whats wrong, help?!

Leeann • Im 19 with a 2 yr old son and had a daughter before him but she sadly passed away after a week. Im with a different man now whom i love to death and he`s great with my son. We`d like a baby of our own
For over 2 years now I've gotten horrible stomach pains shortly after eating. It use to happen every day but stopped, now it happens 1-2 a month. I have agonizing stomach pain and diherrea . The pain gets so bad I tear up. I went to the er once last year and all they did was test my urine and didn't find anything. So idk what it is or what to do. What do you think?