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.
Antibiotics can interfere with your body's ability to deal with estrogen. Estrogen is one of the hormones that controls your menstrual cycle. (For this reason women on the pill are told that antibiotics can make the pill ineffective). Antibiotics also have the nasty habit of giving you a vaginal yeast infection. So watch out for that tell tale chunky cottage cheese like discharge.
Both of these can affect your cycle and make you spot.
If you and your pediatrician is still happy seeing each other, there is no reason to find an ObGyn. Normally you will need to go to an ObGyn once you become sexuallly active with your first exam shortly after you had your first sex or just before you get married (whatever comes first).