is this common?

i hadn't had sex for 1 1/2 years and i had sex recently and it was so painful! but anyway, i couldn't finish because of the pain and i went to the bathroom and there is my period. at first i thought it was just spotting because i didn't have sex for so long but no, its my period, like a week early. its been four days now, and i notice its sorta..well...on the dark side, black even. is this normal?