What Causes Pain At The Side Of Neck With Numbness In Head?

The other day I walked up a steep hill and as I got near the top I had a pain in my left shoulder my neck and my my left gaw, i stopped at the top and rested for a few minutes then I was ok. Today I went for a two and a half k flat walk with a walking group. Then a couple of hours later I had my hair cut, when the girl was washing my hair the left side of my head was tender, later I felt as though my left side of my head numb this lasted for about three hours. I have made an appointment with my GP for Monday.