I would recomend getting a test. Just to be sure. If you got the shot in august and are still having spotting, then you probably arent miscarrying. Im 16 and almost 6 months pregnant. I never bled but some women do. As long as its not really heavy bleeding, you should be ok. And as far as the antibiotics, just discontinue use of them until you find out for sure. I was drinkin like, a week before i found out i was prego and i ended up not rememberin anything and i guess i did some pills and my babys 100% healthy. Im not gonna party n stuff as much anymore, maybe like, once a month if i have a babysitter, when the baby gets older but thats it. so idk if you are, you should be fine. lol