I am getting chest pain when i do activity especially jumping jacks. at rest it eventually is fine again. what is this?

Chest pain : Chest pain with exertion is potentially concerning for a cardiac cause. However, given your age a coronary issue seems unlikely. If the pain hurts more with taking a deep breath or pressing on the area then it is likely not your heart and more bone or muscle related pain. If not, then you should see a doctor to get checked out.

Chest pain: in a 17 yo--strongly suspect some chest wall inflammation ie costochondritis. this should get better with taking it easy--maybe just walking--taking nsaids--ie aleve (naproxen) or Ibuprofen and maybe trying some local heat. If persists --see your PCP