I have mild amblyopia. It was worse as a kid but I had treatment (eye patch for a few years) and it calmed down. Still, it causes minor issues.
I would recommend going to your ophthalmologist because there is a chance they could do something about it. #1 reason I say this is because I basically have glasses to keep my bad eye in line. I cannot tell the difference visually if I am wearing them or not, unless I close my good eye. However, I do get headaches if I don't wear them for a few hours or do a lot of activity that would need the glasses (this time around I'm nearsighted so I have to wear my glasses to drive or watch TV, but often don't bother if I'm just staying home online lol). Anyway, my prescription is minor but it changes every few years (and the change is usually minor; the only reason I get the glasses is because of the headaches). My/my optho's theory is that my eye just gets tolerant of the prescription and needs something new to keep it in line. Like I said I have even had it switch from farsighted for years to now being nearsighted. So, maybe you had your prescription change and didn't realize it because the change was so minor. #2 is that I had some double-vision before this prescription change and if it didn't go away with the new prescription he said I could get a different type of lens to help that, which used a prism. Maybe there is some discrepancy there with your prescription and the optho could advise about potentially doing something different like the prism lens.
That is only my experience, but I think there might be something your doctor could help you with, worth a shot 🙂
My eyes also get tired and I start having double-vision - happened with reading a lot when I was farsighted. My advice for that is just to break it up. Study for a half hour or so and then take a break for ten minutes where you aren't focusing on anything close so you can let your eyes relax. I think this also helps with my concentration too which is a bonus 🙂
