bleeding during and after sex?

sunday morning i had sex, and it was somewhat rough. through your this whole week though i've had very light spotting. however this morning i had ded as well and when i wiped there was light pink blood and it didn't stop for awhile. have takwn 2 digital tests in past 2 weeks both negative. don't know why i'm bleeding. also started depo shot on january 9 and haven't had a period. could the spotting be a very very light period?