My period stopped a week ago and after sex i got mild cramping and pinkish spotting? im also on ortho-tricyclen, what could this be from. never had b4

   Breakthrough bleeding (bleeding at the wrong time)  is very common on birth control.: It happens in about 1/3 of users. Its no big deal and usually self corrects over time.  if you are not satisfied or it continues to happen  then consider using a different birth control method. It is a common side effect and does not mean something is wrong or that the pill is not working.