My period started on Oct. 25 and ended on Oct. 30. One week later on Nov. 6 after I used the bathroom I noticed a very little bit of pink blood; a little more started to come on Nov. 7. I think that it it spotting because it is very light. My fiancé and I do have sex all the time even when I am on my period. I also have a little bit of cramping. So I was woundering why this is happening.

It can be for many different reasons. It may be just irritation from sex, it could be mid cycle bleeding. Have you taken a pregnancy test?
I would suggest talking to a doctor especially if you are cramping.