I had sex for the first time with someone ive been seeing for a week about 3 days ago. I noticed slight bleeding the day after which i know is normal, and yesterday my discharge was fine, but today when i got back from the gym i realised that my discharge was thick and light brown. I put my finger in my vagina and i felt a little bit of pain about an inch in. Is this just old blood and a tear healing? Or could it be more?
Please help! 

p.s. Im on a birth control pill and my period is due in a week. The sex was a little rough, especially trying to get his penis in.