14y/o son has had "heel pain" for about a yr. He plays sports at school. Does this warrant a trip to the dr? Mainly occurs during sport activity...

Athletic heel pain. The most likely diagnosis for your son's heel pain is sever's disease, a condition that is caused by stress to the growth plate in the heel with use of the calf muscles. However, in an athlete, we would want to perform an xray to rule-out stress fracture. If the xray is negative, this can usually be managed with a gel heel cup and exercise program (and he will outgrow it).
Good Shoes? It is most likely a chronic foot sprain, and he needs to wear good shoes to start with. If that and otc nsaids like Ibuprofen do not clear it up, then he should see his doctor.
Stretch heel cords. Sounds liike plantars fascaiitis rest and nsaids good start.
Not uncommon. For severe cases of severs disease or calcaneal apophysitis.
Yes. A year is a long time to have pain..... Have it evaluated.
Usually from growth. This type of heel pain is usually caused by stress at the growth plate of the calcaneus (heel bone) due to growth of the bones of the leg. The bone grows faster than the muscles and where they attach, there is often pain from a traction injury. This can be treated with stretching exercises of the heel cord (find on internet) and a heel cup in the shoes.
Maybe. In active children this age, without a history of injury, this could likely be calcaneal apophysitis which responds well to conservative treatments (good heel cord stretching, icing, and heel cups for padding) and is self limiting, resolving with the closure of the growth plate . However, a trip to the doctor is never a bad idea for radiographs to rule out other causes.
Sever's. Activity related heel pain in a young athlete is often sever's- an inflammation of the apophysis at the tip of the heel. It typically follows rapid growth and can limit activity. Usually resolves without long term effects as growth slows. Treatment usually consists of rest (good luck!) heel pads and stretching. However, a good xray is a must to rule out fracture or other lesions.