Since you are menopausal, please do a self breast exam to make sure there are no lumps.
If it is below the breast near centre of chest..it could be due to gastritis. If on sides could be a muscular pain.
Next Steps
Try local heat application/ ointments. If it increases on taking a deep breath in or if you have fever, cough or breathlessness, consult a pulmonologist.
If there is redness or there are pustules on the skin see a dermatologist.
Health Tips
needs examination to be sure