Masochism from a young age?

From a young age I was masturbating and seeking masochistic fantasies. Through primary school and high school, I would purposely attract this at times. The fantasy would often also involve feet or sneakers. Sadly also, for unknown reasons, the individual in the fantasy would often need to be much younger to make the fantasy more thrilling.
As an adult, the fantasies have stuck and left me confused and unable to have a healthy relationship. I wonder why these fantasies started in the first place – was I abused and don’t remember it?