Pain in right side can be due to muscular spasm
All he needs to do is rest the muscles and avoid stressing
For pain u may use over the counter medicine/ myospaz or any of your choice (only if the pain is more)
Use hotpack for relive
Next Steps
rest
hot pack
mild pectoral stretching
Health Tips
if the pain does not dissolve in 2-3 days consider an in clinic visit to any nearby physiotherapist for physical assessment