It might be an infection, you should visit your doctor asap.
Time to visit your doctor. This sounds very much like an infection to me. It quite possibly is due to the c section operation, I know this happened to my sister and doctor gave her a course of antibiotics to sort it out.
Please dont delay, the sooner you start treatment, the quicker it will clear up. Looking after a new baby is tiring enough,but infection on top of that, you must be exhausted.
Get checked out girl and good luck!