Thank you for the query.
Strained muscle theory is possible. But your pain can be caused by some other reasons like broken rib, lung disorders or gall stones
. It is advisable for you to have at least the chest X-ray and ribs X-ray, abdominal ultrasound
. Fool blood work with liver and pancreas
enzymes should be performed as well. Always when chest pain
appears, heart condition should be checked with ECG.
If this tests will all came negative, strained muscle can be the reason of your pain.
Hope this will help.