Need advice

So my sex drive has been nonexistent and I need advice or just someone to talk to who has maybe gone through this. Ever since I had my baby 11 months ago and got the paraguard IUD, I literally never want to have sex. I never get horny, and my fiance lately has been telling me he feels like I'm falling out of love with him because I don't initiate things and he feels like I'm not as attracted to him. That's literally never been the case, even when I was pregnant I wanted to have sex constantly and was always horny. This IUD makes positions hurt, and usually gives me cramping after sex, but it never stops me from doing it. I don't know if it's the IUD that has fucked up my sex drive or something else, but I used to initiate things and be more sexually active with him before I had my baby and I don't know what to do. I've been trying to initiate things more, but mostly because I know he wants me to, not because I'm actually in the mood to do stuff. Advice? Has anybody else gone through this? Should I book an appointment to see an OB? I don't know what's wrong with me, because I'm more attracted to him than I am to anyone else, but I'm just never horny.