I Just Had Umbilical Hernia Surgery Last Wednesday, Pain Is

I just had umbilical hernia surgery last Wednesday, pain is localized in the abdomen. Surgeon prescribed Codine and a stool softener. I took the codine three times last week and the softener only on Friday afternoon as I had not had a bowel movement yet and nurse told me to take it to help. Now I am having very acidic diarrhea. Is this normal? How do I make it stop, it really hurts my anus.