When ever I wear sunglasses after 5-10 minutes I get this sharp pain in the back of my head ,I thought it was the sunglasses but it happens with all of the sunglasses I have tried. A few days ago I was wearing my sunglasses again and I started to get the sharp pain I thought I'll try to get through it but the I started to get spasms in the back of my head. So my question is why is thos happening sorry for the long writing.thank you.