I Went To The ER On Sunday Due To Pain

I went to the ER on Sunday due to pain in my stomach, they took blood and urine sample and did ultra sounds but everything came back good. They gave me anti nauseous medicine and told me to get antacid medicine. I haven't been able to eat much. The medicine and antacid seemed to help for the first few days, but I'm still experiencing pain again and passing yellow stools. What should I do?