PCOS , 50mg Clomid and late period

Hi everyone. I'm currently TTC #2. I was in Clomid 50mg days 5-9 , I'm currently on cycle day 36. This past Thursday was the last time we BD, on Sunday I had SUPER thick EWCM, I was a little crampy on Monday. On Tuesday mid day I got really bad cramps and then had brownish pinkish discharged (just thought I was starting AF) well Wednesday nothing normal day no spotting or cramping. Today I had I tiny bit of blood with a tad of cramping but nothing since. I called my OB and she asked of I have taken a pregnancy test...which I did today and it was negative. I've had headaches, super fatigue and constantly feeling like my bladder is full. Does anyone know what could be wrong?