Strange feeling in head when stressed?!

For example today, when the teacher said 10 more minutes left for the test and I realized that I hadn't done much, I suddenly got so stressed out that I felt a HUGE rush of blood to the head. This rarely happens to me but when it does, I feel something (maybe a vein) on the right side (only this side) of my head start pounding and it feels heavy for quite some time. Then its followed by periods of lightheadedness. This is not my usual reaction to stress. I consider it extreme. Im only 20. Im usually calm but I can't help it when something like this happens. Is this life threatening?