please help me im scared. (TMI)

my last period was 6 days ago. 
past two days sex with my boyfriend has been really painful. 
i was masturbating just now and noticed a lot of blood. a lot. apparently it soaked my underwear already and when i went to the bathroom i noticed a couple chunks of it and just a lot of blood in general. 
what's up with me?? i'm really scared.