What Causes Delayed Periods After Taking Antibiotics?

I m 19 years old. I got my tooth pulled last week, and they put me on Clindamycin and vikodin for the pain. I was getting a lot of discharge and I was four days late. I had protected sex with my boyfriend and then the discharge stopped and now it s 9 days late. I ve been having a lot of anxiety lately and was wondering if maybe either stress or the antibiotics were the cause of my very late period. I normally have irregular periods, but I m getting nervous. I don t have any symptoms of pregnancy besides minor constipation. help me :(