blood after fingering

F (15) i spent the night at my girlfriends house yesterday and she was fingering/fucking me and after she was done i started bleeding. i thought i started my period but it wasn’t like… period blood yk?? then i started thinking she cut me with her nail on accident but it didn’t hurt or anything. at one point she went really far in so could that be the cause of it? and then this morning, she was rubbing me over my underwear and when i went into the bathroom to pee i had a bunch of brown/red discharge?? (also i’m not supposed to have my period for a few weeks)