Girls, hi! Yesterday I had intercourse (since childbirth was 5 weeks a…

Girls, hi! Yesterday I had intercourse (since childbirth was 5 weeks ago, 4 days). The discharge ended at that point, they were weak, some light colored. Practically none. So after intercourse there was blood, then brown, then red, yesterday scanty, today more. Can you tell me why? Maybe someone else has experienced this. Many write that they start having sex earlier. In my discharge note it said 6 weeks, no ruptures, felt good.