Mirena period question

So I got the mirena put in and a week later I started my period. I’ve now had my period for a little over a month straight. No breaks in between and it’s been heavy with very painful cramps. It’s exhausting. Has anyone experienced this? I called my doctor but they haven’t called back yet so I’m just wondering. Idk if it matters but I also had a baby 4 months ago and this is my first period since giving birth.