Mirena pregnancy? Maybe just hormones? Help...

So I’ve had the Mirena for 3 months now. I have had unprotected sex about 5 times since.

The past 4 days I’ve been sooo nauseous but other than that I’m not sick feeling. When I try to eat it makes the nausea worse. My periods are very irregular now so I have no clue when one is due...

Do you think this has to do with the IUD? Do you think it could be a pregnancy? I have no clue what’s going on but I’m miserable and it reminds me of morning sickness with my son.

Id go buy a test but I don’t have the money to right now...