HI Nonnaluna, welcome to the board
. I've never tried calciton so i can't help there, but i have been taking Strontium citrate for over 5 years and have seen gains with each DEXA. There is plenty of info about it online if you'd want to read more about it. I've had no side effects from it.
Exercise is important in bone health and, like Jane said, walking alone may not be enough. Weight training, impact activities and just keeping in motion are all good for the bones and the rest of you too. Balance is important too since it will help you from falling. take care, phyllis