To worry or not to worry?..

So last night my partner & I were intimate & when we finished we realised that there was blood on the sheets... We don't know which one of us it came from but we assume it's from me. I'm freaking out because it has never happened before - besides my first time of course. However I am on the pill for birth control & I have skipped my periods the past 2 times & it could be just from being intimate but I'm not 100% sure & we weren't really rough. Should I be worried?..