What could cause a sudden feeling of blood running down on the back of the head (internally) along with heavy legs and lightheadedness and weird hollow burning feeling inside ears?

At your age probably nothing serious. When you have that feeling again- sit and relax and take a few slow deep breaths. If it persists then see your MD for a check up. Good luck

Instead of trying to guess at the causes of these potentially serious symptoms, one should see the PCP as soon as possible with the intension of seeing ENT/ Neurology Consults. One should also check their Daily BP.