Heavy Bleeding After Sex

Hey ladies!

So I was celibate for 2 years and recently been dating someone and we had sex. The first time we did I bleed a little which I expected but this second time (which was about a week later) I bleed super heavy like it definitely looked like I was on my period. I'm just wondering if this is normal. Sex was a little rough but it felt good I had no pain whatsoever I'm a little sore now in the groin area but that's about it. Has anyone experienced this as well?

Also I've been on mirena for about a little over a year now if that makes any dofference.