Thanks for your question on Health Care Magic. 
I can understand your daughter's situation and problem. 
No need to worry for heart related diseases because her ecg is normal. 
Possibility of 
musculoskeletal pain is more. 
But better to get done chest x ray to rule out 
pleurisy. She is having 
chest pain on deep breathing. This is seen in pleurisy (inflammation of 
pleura). So get done chest x ray. 
I'd this is normal than no need to worry for pleurisy. 
Musculoskeletal pain is more likely in her case. 
So ask her to avoid movements causing pain. Avoid heavyweight lifting and strenuous exercise. Avoid bad postures in sleep. 
Give her painkiller and 
muscle relaxant drugs. 
Apply warm water pad on affected areas. 
Don't worry, she will be alright. 
Hope I have solved your query. 
Wishing good health to your daughter. Thanks.