Thanks for writing to us.
The burning pain below the left armpit is likely to be due to a nerve root
irritation at the level of cervical or thoracic spine. An MRI
scan will help in detecting the cause.
I hope this information has been both informative and helpful for you. You can consult me again directly through my profile URL http://bit.ly/Dr-Praveen-Tayal
Dr. Praveen Tayal