Amicus,
my Dad had Rheumatic fever as a kid and damaged his heart valve, actually 2 of them, but he made it to 90! He had lots of tests and even by pass later in life and then a pacemaker, but he managed!
Dad worked hard his whole life and when he got home, Mom had a "honey do list" as long as his leg! So he was rode hard and put up wet often enough...
I developed allergies, or was diagnosed thus, in 2nd grade and took shots for over 50 years! Still struggle with allergies, especially a couple gnarly food allergies that preclude me eating out or other's foods at bazars..
Alas, none of us get outa this world alive so whatever is, IS and--- shall be...ZACH will cope and do fine...
I can understand his reticence regarding track, but living well sometimes means giving up stuff we'd like to do...
Finding out our limitations is about all the medical community can do for us, I'm afraid...but that might be a stilted view given my recent experiences...
prayers up for young Zach....