Welcome to HCM
We understand your concerns
You did consult a physician for your daughter and he told nothing to worry. Your daughter is young and energetic, so the doctor after examining her externally might have suggested that it is just a muscle pain
. If you consult once again he might suggest an EKG to confirm the heart is fine. The pain could be due to gastric derangements and anxiety
also. Gastric derangements press diaphragm upwards and creates discomfort to the chest are which is mistaken as related to heart. Mind takes over from here and strts worrying and leads to anxiety. Worries and anxiety increases pain and that is it.
Anyway consult the physicn once again and follow his advice.
Good luck to your daughter