R.B.
her breast growing is why her nipples hurt. Try a sport bra, that might help. If it doesn't, don't allow her to walk around with out anything on... she needs to be in her bedroom with out it on, in private. She is starting to devlop she needs to start learning the privacy things.
With her period it can take up to the first year after she gets her first one before it becomes "normal" and trackable. There is nothing to worry about.
:)