Brown tar like blood after antibiotics

I am 30 years old and recently was on a very strong antibiotic for an infected tooth. I am now having some snotty brown color stuff come out and it started 7 days after my cycle ended. I was just wondering if it could be the antibiotics messing with my system or could there possibly be something else going on. I have been having this now for 3 days and sometimes it looks like a really like period. I was also on pain killers and took lots of ibuprofen as I had my wisdom teeth pulled. Thank you for any helpful hints.