What Causes Heavy Bleeding During Pregnancy?

hi.. i had a termination in january, had a normal period in feb and then on 27th of feb i was due on anyway and i started to bleed very heavlily. i went 2 hospital and the doctor said it could be heavy period or infection but gave me nothing.. i was in alot of pain .. and still now 9 days later i am still bleeding and have severe pains in my legs?? doctor did pregnancy test and was negative. also during past few days i have intercourse witth mypartner as i stopped bleeding for a day and as soon as we had sex i started to bleed again :( my body jst feels so achy all over and dont know why i keep bleeding cn u help? or give me advice? im going to docs asap but thoguht id ask. tara