Episodes of dizziness, loss of balance, and sleepiness

For the past two years I have worked at a car manufacturing company. I work on an inspection line which means cars come past me approx. every 50 seconds. I must inspect 400 to 500 cars a day moving past me at 50 second intervoles. Since I began this job during the inspection process I experience episodes of headaches, extreme dizziness, sleepiness, and loss of balance. Sometimes lasting an hour or so at a time. I feel as if I have turned crossed eyed often times not aware of my surroundings and as coworkers have told me I have the appearance of being intoxicated. My eyes turn red and I constantly feel as if my legs are going to give out and I am going to fall down. I am not sure if this has to do with my focusing on the car to look for defects or the motion of the cars going by. My episodes are getting worse. I am at the point that I feel as if I am going to lose my job because people or starting to think I am on drugs. And I am not. I don't know what to do. I become completly delusional during these episodes. This only happens during work when cars are going by and sometimes while driving. Now as I look at these cars there are bright lights that shine on the car. I often find that I get to the point that I can no longer see the actual car but rather just the lights. Thats when I feel crossed eyed I have to look away and shake my head making myself refocus on something else in order to be able to see correctly again. When this happens is when I usually look down to shake my head often times the ground doesn't look right I can't tell where it is and where it begins making me almost fall down. I get plenty of sleep and have taking everything now from caffiene to vitimans nothing helps. When I walk away from the line I am fine, it is only during driving and looking at the cars go by. I am not sure what could be wrong and who if anyone I should see about this. Please help, I don't want to wreck or lose my job! THANKS!