Post Sex Bleeding

I recently got my IUD (second one I’ve ever had) 6 weeks after my son was born, about a month ago now. It seems as though every time I have sex I start bleeding again? I know bleeding is normal for first 3 to 6 months but it seemed like I’d almost stop and then I have sex and it’ll start as like a tiny bit of brown discharge the next day and then the following day it’ll be fresh red blood. It’s been about 3 years since my last IUD was put in so I don’t remember it super well. I don’t have any cramping other then occasionally and I can feel my strings. Any ideas?