Hello Kathy135 and thanks for posting, 

This bleeding could easily be nothing to worry about and linked to being on the pill, but unfortunately, no one here on Cancer Chat can say for sure why this is happening. So our usual advice about something like this is to talk to your GP or practice nurse and get some input from them. If necessary they can call you in and take a look to your cervix to check it is looking healthy.

Try not to worry, but get some proper advice about it when you can to be on the safe side. 

All the best

Julia