My eyes used to bother me a lot whenever I used one particular PC at home. It bothered me even after only using it for a few minutes to check e-mail. I never had any problems at work though-even after 10+ hour workdays As it turned out, the refresh rate on my home monitor was set too low at 60Hz. It was the flicker that was causing my problem. After changing it to 85Hz my eyestrain problem vanished. You could try checking the refresh rate of your monitor, to see if it's set too low. Hope this helps
If you are using a desktop computer you can buy a protective glass, and when not typing keep a safe distance of about two feet from the screen. By the way i am a doctor. if you are using laptop it should not be a problem. the eye problem may be just a coincidence with you starting to use computer