I Had Iui Treatment At 9/08/16 And I Used Susten

i had iui treatment at 9/08/16 and i used susten 400mg/day. after the 15th day of iui 24 aug i took hcg urine test shows -ve, at 18th day 27 aug test shows -ve. my doctor asked me to stop susten at 18th day itself and i got bleeding on that day and next day. shall i take hcg again or it is periods