Eye Strain, can I regain my vision?

Today I applied for a job and part of it is a preliminary general physical exam, one is vision test.

To my surprise, I can hardly guess the letters on that chart. It's the first three rows of the smallest font. Before I feel these headaches that I assume are related to vision, I see the letters crisp and can guess them easily if they are too small. Even the test for color blindness, I had noticeable lapse, when before I can guess them quickly and perfectly.

I have been using my eyes extensively and it's been abused or overworked for the past 3 or more years.

My question is, is there a possibility that I can regain a 20/20, if it's only eye strain. I don't wear eyeglasses and I don't find any need to. I can still easily shoot a thread in a needle's eye. I can read New Times Roman font in MS Word up to font 6, I guess. But is it enough? Sometimes my vision blurs slightly and sometimes I feel fainting, and many times I feel headache, but not something unbearable like migraine. Just a feeling like what I see is not steady, and when I try to focus my eyes hard, say on a code in front of a computer, or an animation in a game software, then I feel that painful feeling on a part of my head, plus that dizziness.

What can I do about eyestrain if anyone of you experienced it, and who is the physician to go to? Is it the optician or it's better to go to a general phycisian. I hesitate going to an optician because I am afraid they would just make me order prescription eye glasses.

I need a physician that can diagnose what is my condition, and what is that physician called.