Suggest Treatment For Pain And Tenderness At C-section Site

my wife had undergone a cesarean operation 4 months back all the wounds healed but after 3 months again the pus formed. The doctor made another incision and said that all the stitches have healed and everything is ok but she continues to feel the pain moreover the area operated seems to be very tender, puffy, red and painful when touched. What should be done to rectify everything