What's going on?

Okay, well I became sexually active with my boyfriend in April. For the first two months after that we basically did it, A LOT (TMI). Now we don't do it as much but we still get the deed done. The last two times we've done it I ended up spotting very lightly after but it eventually went away by the next day. This has never happened to me before so I'm confused and a little frightened. Could it be because he possibly hit something in there? Any advice or similar stories & how you handled it would be appreciated. thank you.