Birth controls can definitly cause some bleeding between periods and irregular periods, especially if just starting or coming off of the birth control.
I don't believe his fingernails would cause any damage. Unless he has them unusually long.
I think your slight bleeds are from your birth control, which I wouldn't worry about, especially if you aren't feeling any pain.
Good luck and Best wishes! :)
and i was going for similar reasons!
she explained that bleeding in between periods is normal (to some extent) on the pill.
she suggested to write down when the bleeding comes for the next several months (after intercourse? after fingering? randomly during the cycle? mid cycle? right before or after a period?). From that she should be able to tell if it is a problem due to the pill that would then need to be changed, or a problem elsewhere (she quickly mentioned cervix although not quite sure about what she meant exactly).
Just note down this time and the next times :)
Hope this helps!
whatever you do don't stress out and keep it going with your man! as long as there is no pain then fingering or any other activity is totally ok to be continue :)