What Causes Periods With Odor, Redness And Clotting Along With Weakness, Dizziness?

I started taking a birth control pill on 31st august 2014 to prevent birth after having no periods a month before (last period date 6th July 2014 and after a negative pregnancy test). I had my periods on 24th September 2014 and finished on 30th September 2014 then my husband and I had sex the same day. My periods have started again on 1st October 2014, foul smelling and bright red in colour with clots. I am feeling weak and dizzy. What should I do?