I Had Unprotected Sex On August 21 And I Used

I had unprotected sex on August 21 and I used protinor that very day so I saw my period few days after which was on 26th of August..so few days after my period ended I had another unprotected sex which was on September 2nd and I used protinor again the next day, another few days later I had another unprotected sex but the next day I noticed light blood...please what is h
appening to me..is it the effects of the protinor or something else