Hi lillibet :)
See your doctor, but until you do, here is some information you might take a look at. Also I know that heart related chest pain is not brought on by pressing on the chest area. (I am not a physician, so I don't KNOW anything but I think :) )
Background: Chest pain is a common reason for parents to seek medical attention for their children. Annually, physicians evaluate approximately 650,000 cases of chest pain in patients aged 10-21 years, a number that may reflect overwhelming concern about chest pain as a manifestation of cardiac disease and cancer in older patients.
Costochondritis is a common cause of chest pain in children and adolescents. The condition is characterized as an inflammatory process of 1 or more of the costochondral cartilages that causes localized tenderness and pain of the anterior chest wall. Most cases of costochondritis are idiopathic. The remaining cases may result from costochondral irritation due to direct trauma, aggressive exercise that caused a strain, or a prior upper respiratory tract infection with cough that caused repeated stretching and strain at the costochondral junction.
Costochondritis is a relatively benign and usually self-limited condition. Patients are often evaluated initially in the ED or, with acute conditions, in their primary care physician's office.