I have the same thing. I noticed mine right before my menstrual cycle a few months ago. It started with tenderness in the armpit, but then it would go away. Now I have tenderness in the armpit and my right arm and hand go numb. It comes and goes. today is a good day, who knows what tomorrow will bring. I went to my dr., and I am having an ultrasound on Friday, and an EMG on Monday. Go to your Dr., my motto is: when in doubt, check it out.