That makes sense - I've seen an awful lot of injured 14-year-old distance runners in my time (that's about where you are, isn't it?). Not unusual to have injury problems when a growth spurt's happening. My main piece of advice would be to get it properly looked at by someone who knows what they're doing (probably not so easy at this time of year).
(If it's any encouragement, once I'd gone through my own bout of this, ankle/heel in my case, and got it sorted - about a month on the sidelines in my case - I then didn't miss more than a day or two at a time with injury for another 11 years).
I don't think I knew what exercise was until I took up rogaining (at age 16) although I did ride to and from school from age 12 and onwards so I never had this issue. I think doing rogaining first (long, slow) helped strengthen up my legs and ankles as I never suffer from rolled ankles as many orienteers do although it meant I was never a particularly good orienteer, having lacked precision navigation training from an early age.
Of course I now have my worst injury from an impact rather than overuse so I haven't saved myself anything in the long run.
(Your resting heart rate of 24bpm is a little on the low side)