On occasion,When I do strenuous physical activities such as playing sports, I will start getting blurry vision in either one eye or both. Its almost like I get tunnel vision which makes it hard to see at times. This blurry vision almost looks like a mirage image in the corner of my eyes. After a little time passes, I will start getting a severe headache with sharp throbbing pains going from what feels like my back wisdom tooth/jaw area, straight up through the middle, left part of my brain. It only happens in the left part of my head. I have seen a specialist and they said it might be caused by dehydration but no matter how much I hydrate before hand, it still happens. This headache will cause me to vomit. Probably the worst pain I have ever been through. What can this be? Ive been told its not a stroke or heat exhaustion as I work in heat constantly and it only happens an times I play sports. I have also had an MRA done that didn t show anything out of the normal.