An optometrist goes to college for a basic degree, then 4 years of optometry school to become a doctor of optometry, for vision and eye conditions.

An ophthalmologist goes to college for a basic degree, then medical school for an MD, then specializes in conditions and diseases of the eye. Usually this also means they may specialize in certain specialties of eye problems--a glaucoma ophthalmologist, a retina specialist, a pediatric ophthalmologist, etc.

I would say go to an ophthalmologist, and one who specializes in eye movement disorders. Find an ophthalmologic practice with more than one doctor, and ask them to make you an appointment with the doctor who best fits your symptoms (which you of course tell them, at least briefly).

A very good optometrist would also know what is going on with you, but an ophthalmologist would likely be better.

(I have a few different eye problems, and see two ophthalmologists regularly, as well as up to three or four other ones in this practice occasionally/yearly as things act up.)

Your eye muscles, as well as the vision nerves and what happens with the images sent in by your eyes is all under control of your brain, so it is not unreasonable to have visual problems. Could have been something that was there before, but you could overcome it and never noticed, or it could be something newer. When I'm tired, I have all kinds of trouble that much of the time I can compensate for. (When I go in for exams, the doc usually ends up having to tell me, will you quit controlling it already! (nicely, we know each other well) because I am so used to fighting the problem that it's hard to let it go so he can see how "off" things really are. And there are many easy ways to help a vision coordination problem like that, so don't be too distressed, just go get checked out.