IUD questions

So I got an IUD placed this past September. And I just started getting my period again 3 months ago (I had a baby last summer). Anyways, I had sex for the first time since I’ve had my daughter about a month ago and I’ve been lightly bleeding ever since. And then I had sex with him again last night and I started actually dripping blood everywhere. And the guy (I’m dating him, fyi) said that he thought he felt something during it (like inside me), and now I’ve been bleeding more since. Is this normal..? Or should I be worried..?