Need some help really fast?

Hi , I know i might be freaking out about nothing. or might be something but its a bit freaky. anyway so 2 days ago * after having sex * i started bleeding with blood clots* dunno how to spell it* and brownish /reddish blood. i put on a tampon and got happy coz my period is 2 months anyway later on i fell asleep n woke up maybe 9 hours later , freaking out my pants would be full of blood i went to change it to my surprise the tampon didnt even get full it was only have a side of the tampon of brownish blood and not even alot , this has been going on for 2 days now the tampon is only half of blood on 1 side n its only brownish blood * like the blood has been left for a while* n its freaking me out , i read up on abnormal bleeding and started freaking out more . im 100% this isnt a period coz i bleed heavy n takes alot out of me. i cant rly go to the dr coz i dont wanna scare my dad with a sex diesses * hes old n still thinks im innocent* so if someone could answer and relax me a bit, + i took a pregnancy test twice its negetive n i did bleed once before a little bit n it stopped was bright red . if someone could plz help me :( im rly scared