I get this weird cool sensation at the back of my head. It doesn't feel like a headache. It's sort of relaxing but it worries me because about 2 years ago I almost lost consciousness while traveling, my vision blacked out n i couldn't hear anything for a few seconds. It was probably due to weaknesse but i remember i had a same sensations, as if a thread broke in my head. Since then i get this sensation every now and then i wonder if it's serious.