13 weeks postpartum brown discharge

Brown discharge at 13 weeks postpartum can sometimes be the start of your period returning, especially since breastfeeding can cause it to come back in irregular ways at first. That said, since you had a csect, it is really worth bringing this up with your gynae or at least your polyclinic doctor just to be safe and get a proper check. It is totally understandable to feel worried but you are doing the right thing by flagging it early, so please do not sit on it too long.