First of all be clear in your mind that it is not a heart problem.
1... Heart pain doesn't increase or decrease on changing sides and is accompanied by some restlessness
,constriction in chest and uneasiness.
2... Heart pain doesn't occur on exhaling only.
These all are symptoms of muscular strain.
Take some anti inflammatory like ibuprofen
400 mg three times a day for 5 to 6 days.
Do Local hot fomentation
Avoid weight lifting.
You should be all right soon.