What Causes Vaginal And C-section Incision Site Discharge?

My friend just had a c-section on December 18. She also got her tubes tied at this time. However after her incision healed she started leaking a yellowish bloody discharge from her vagina and her incision site. Now the incision is opened back up on the left and right sides, and the discharge is worse. Her doctor has perscribed her Keflex and she has already taken the full course and he has perscribed her another course and sent her for a CT scan. He isn't giving us any answers and we are really concerned. What could be happening to her?