I get a sudden feeling of tiredness in my shoulders that travels up my my neck to the lower back of my head. Not very painful, after a few seconds it subside. The feeling then travels down my arms and they start to feel weak as if I cannot lift or move them. This was happening about three to four times a month, but, now it is becoming more severe, happening once or twice a day, skipping a day here or there. I've gone to my doctor and explain this and he said that because it wasn't happening very, not to worry. But, I do worry and want to know what might it be? It appears neurological to me because it travels from one region to another, but, I'm no doctor. What could be causing this?