sex hurts??

my boyfriend and i have been having sex for the past 7 months, like a lot... but just recently its been hurting, not when hes penatrating me, but when he first sticks it in or when he tries to finger me, it stings/burns and then its a bit sore, we fuck many times in 1 night and its still sore the rest of the week now... i just dont know why its hurting?! help!!