11 yr old daughter has aching right upper chest pain, (no arm pain) when she raises her right arm or bends over, effects breathing, stressed at school ?

Could be....: ....Stress. It could also be a pulled muscle. Or it could be something called pleurisy, which is inflammation of the lining of the lungs and involves pain that is worse in certain positions and with deep breathing. If she is otherwise well, without cough, fever, etc., then try ibuprofen. If she's otherwise sick, see your doctor for a proper evaluation.