IUD and unprotected sex.

Hannah
So I had unprotected sex [about 2 weeks ago] on the last day of my period and it was very light. He finished in me twice, and I'm nervous about being pregnant. I know that the copper IUD I have had like a 99% prevention rate but I'm still really stressing. I'm in mid-ovulation right now and I'm getting a brown discharge. I looked into it and it seems as though it's mid ovulation spotting....but Idk! Any ideas I'm just very very anxious and stressed. 
Plus this is the only thing that's been off since then.