I Had A Total Right Knee Replacement April 4th. I

I had a total right knee replacement April 4th. I have diarrhea for 3 weeks. My surgeon sent me to my GP. She ran numerous stool tests and found nothing. I am still in tremendous pain, my stomach is gurgling all the time, my knee is still swollen and feels hot. After almost 4 weeks I think something is wrong like I have an infection.