Could I be pregnant?

So about 2 weeks ago I had unprotected sex. Well anyways I’m on the IUD so I thought I was completely protected, however a few days ago I thought my period started but I only bleed a little and for like half the day. now I’m having this kinda thick brown discharge (been going on for a couple days) I’ve been super tired and my mood have been a little off. I also have been having some back cramps along with those I’ve had very mild pressure/ cramps in the normal spots. I’m kinda bloated as well. I’ve never felt like this before... idk if I’m just getting sick maybe or if I might be pregnant. The internet has me a little scared about an ectopic pregnancy or something.