The most common cause is cervical compression of nerves C1-C3 secondary to spinal stenosis. Stress can be a factor by causing musculature to squeeze the tissues. So can blood high sugar levels by altering osmolality.
The definitive method of differential diagnosis is simple (You don't need an MRI):
(1) While experiencing symptoms apply axial traction. If the symptoms immediately diminish you have your problem identified.
Thanks for you input.....I wasn't suggesting I had worms around my shoulder area :-)
It was the best way I could describe the feelings. Maybe tingling would be a better description. It comes and goes. Could be the nerve endings, Who knows.
Have a good day.
Although unlikely they could in fact be "little worms". These sensations are consistent with a filarial worm infection. Virtually unknown in the United States, these creatures are happy campers in many parts of the world. They infect food and then grow and end up in...well the shoulder for one place.
Unless you have been overseas, or have eaten unauthorized imported food, this is highly unlikely.
Outside of that, I'm open to suggestions.