Three weeks post op umbilical surgery. Should I be worried about the diarrhea? Pain?

Hello,
I am sorry to hear about your challenges with umbilical hernia. 
The diarrhea and pain you describe are abnormal and should be evaluated by your surgeon. Regarding the diarrhea, please consider whether you made any changes to your diet after the surgery that may account for the change in your stool. 
I recommend you make a follow up appointment to discuss your symptoms and concerns. 
Best wishes,
Dr. Moein

You need to check with your doctor about the diarrhea. If you took antibiotics it could be from an imbalance of good bacteria in your GI tract the most serious can be an overgrowth of Clostridium difficile. It’s also possible that you have a viral gastroenteritis unrelated to your surgery. She Check with your surgeon or primary care doctor and she/he can determine what testing is required to make a diagnosis.