Prolapse surgery complication? Please answer?

My mom just had a prolapse surgery or hysterectomy, last week. She was in the hospital for 3 days, now she is back home. All is fine, except that a day after the surgery, every time she eats something she has to go let it out (Going to toilet), she also suffer from loose motion / diarrhea? We asked the doctor, he said it's cause of the medicine being too strong, so my mum stop taking the pain medicine and the antibiotic for a day, but she still having loose motion. Is there any complication? I'm worried, we are going back to the doctor tomorrow, I'm just wondering for suggestion. Thanks.