Okk, so i have a womanly question?

hello. well this isn't a question really. my thing is i last had 3 days ago, and this morning i went to the bathroom and noticed that i was spotting. i thought that was a tad odd considering i had finished my period last sunday. I'm on the pill. but i was wondering if anyone knew what it could possibly be. i know its not a UTI. i don't have to pee frequently, but it does kind of sting a little when i do go. this has happened before a couple of times and it has gone away, but i was just curious if anyone had experienced this or knows what's going on. thank you!