What Causes Right Sided Stomach Pain After A Full Hysterectomy?

hi ! just resently had my full Hysterectomy procedure.. after 10 days i discovered severe pain on my right side of my stomach where my Dr. took my ovary. i started bleeding and in pain all the way the back of my pelvic. Next day went to see my OB who performed my surgery, she sent me to get blood test and CT scan right away.. after few hrs. of waiting found out i had a bad case of infection and it is in my blood. i got admitted right away back to the hospital 2nd time to have another procedure done. Another incesion where the bacteria is forming to try to sucked up all the infected area (blood) and end up carrying a tube for the next 7days. Found out i have E.Coli infection...HOW this happened.. i need 2nd opinion besides my Dr. telling me..Please !! i need to educate more about this issue.