Well I Have Been Having Sex With My Boyfriend And

Well i have been having sex with my boyfriend and that was when my period started when it was light and he ejaculated both nights and then when my period finished we done it again and he ejaculated yet again but a couple of weeks has passed and we are having sex every night to every 2nights and i went to toilet and urinated and wiped myself and seen that there was a wee bit of light pink blood? What could it be? Ive only had one sexual partner...could it be because ive not been wet enough when he has inserted? Any ideas what it could be