Thanks for writing to us.
I am Dr. Vaibhav Gandhi, I am Orthopaedic surgeon
According to your history most likely you have injured sternum
Other possibility include congenital pectus excavatum
you can send your clinical photograph ,
Or consult orthopedic or paediatric surgeon
I advise you to take x ray
chest ,take analgesic
,rest and clinical examination from surgeon.
Hope I answered your questions.