Gave birth july 23 via cs. had unprotected sex last sept 23. sept 25 i start to bleed until now. what's that supposed to mean? is this menstruation?

Yes and No ???: Vaginal bleeding that persists for more than about eight weeks after delivery is unusual and may be due to infection, retained products of conception, a bleeding diathesis, or, rarely, choriocarcinoma or a uterine vascular anomaly, as well as other causes. A temporary increase in bleeding at this time may represent menses; in such cases, bleeding should stop within a few days, or pregnancy?

See an OB/GYN: This could be several different issues. Although it could be menses, there are other possibilities and you would need to be examined in order to establish a diagnosis. See your ob/gyn doctor and be evaluated. Good luck.