Strong ache under the arm pit on the chest side radiated later to the shoulder blade, then down to make a band on the left upper arm. pain stronger when standing. nothing done to cause muscle strain.

Go to the hospital: The symptoms you describe are very concerning given your age. Without something that makes you think of a muscle strain, this is even more concerning. If you are short of breath, nauseated, have palpitations or are sweaty, please seek care immediately. Call 911. This can be a heart attack or a problem with your aorta. I hope it is neither of those things, but you should be seen asap to be sure.

Requires Examination: While this sounds neuromuscular in nature involving your ribcage or shoulder, i would advise being examined by your physician to also make sure this does not represent a problem in your chest or a pinched nerve in your neck or should area.