Today During My Normal Workout Routine At The Gym, I

Today during my normal workout routine at the gym, I experienced dizziness and lightheadedness so severe, I thought I would pass out immediately if I didn't lie down. On my short path to a bench (10 feet to 6 steps down and turn the corner to the bench) I found that by the time I got to the steps, both my hands were numb and couldn't grip the railing, and that I seem to have lost control of my feet since when I went to step down one step, the foot wouldn't flatten out on the step. I sort of involuntarily tiptoed down the steps and stumbled onto the bench, where after about a 5 minute rest felt well enough to walk and complete a toned down version of the 4 remaining exercises in my normal routine. Then later, after a shower and getting dressed, the dizziness returned and I had to lay down in the locker room. What do you think could be causing this?