6 yr old has had chest pain for 4 mo. w/ activities but can't figure out what causes the pain

My 6 yr old daughter has been complaining of chest pain for 4 mo. now. For the first 2 months I kind of blew it off. I told her she was fine, she would come in from playing outside and tell me that her chest was hurting and it feels like someone is punching her in the chest. After 2 mo. of the same complaint I made an appt. Dr. told me to just keep an eye on it. So, she kept complaining of same thing. But new complaint with chest pain now, she would tell me her right jaw would hurt her. Not her teeth but under her teeth, she pointed to her lower jaw. Dr. referred us to pediatric cardiologist did echocardiogram and holter monitor all normal. Just a heart murmur was found. Went back to family dr. and tried blood work and other test for gallbladder, kidney, and liver. All normal. Can't figure out what would cause chest pain. She only complains of chest pain with any activities, such as gym at school, running, playing outside, jumping around the house, ect. It does not hurt her to push on chest; she does not have a cough. It hurts for about 15 min then it’s gone. Mainly on right side chest pain, right side rib pain, and right side jaw pain. Is there anything else we can look for or test that would help pinpoint source of chest pain?