palm side, top of hand?, finger? wrist?, is it sharp pain, dull ache?, does it feel like it the tendon or something else? Hand pain ain't very specific. Anyhow if there's pain that likely means you ain't doing something right, probably bad playing habits e.g. tensing up alot, or slamming the keys. Or it could be something you doing outside mania, I dunno. Ain't a doctor nor a physio, but I can't imagine playing through pain everyday is good for ya.
If you can figure out what's causing the pain. Then that'll help fix it. Anyhow, I recommend getting it checked out by a doc or physio.
As for the blurry vision, not really sure. Maybe try lowering the scroll speed a bit?