Talk to Gynecologist on Prolong Periods

I got my periods on March 13 and they ended on 21march we had unprotected sex on 27march and on 28march evening I took ecp only 1pill. And from 29march I am having periods. In the initial days they were like brownish black discharge but since Monday 6april they are red blood with clots today I passed a sac like clot which was in red and white color I got my bhcg done which was negative. What should I do now. Is it a miscarriage?