Can antibiotics cause spotting?

I'm 18 and I recently I had a staph infection in my lungs. I was put on amoxicillin for 10 days; 2 capsules twice a day. About 6 days into treatment, I had some light spotting. My last period ended about 2 weeks before so I thought it might have been ovulation. However, the spotting continued sporadically over the next few days; bright red, but not heavy or constant enough to be a period. I finished taking the antibiotics a little less than 2 days ago and the spotting stopped. Just now the spotting came back. I read somewhere that some women experience irregular spotting due to antibiotics, but I'm not sure if that's true. I haven't felt any pain or symptoms of a period. My periods are usually very regular and predictable. Also, I'm a virgin and not on any birth control. I've never been to an OB/GYN (I still have a pediatrician). I'd really appreciate some answers.