Hi,
Chances are more in favour of a muscle pull or muscle spasm. You could try some warm compresses, rest, local
analgesic gels and oral pain relief medications and see if it helps with your symptoms. If the pain persist,
you would need to consult your doctor for a clinical
examination and maybe a chest xray if required. If it is aggravated with breathing, you should get it checked
urgently. If it is a muscle pull it would resolve in a couple of days. Do not do exercises or lift heavy
weights for some time. Regards.