Eye pain/strain only when looking at screens?

I'm 19 and have been very active on computers and other screens for many years and never had any problems. I have glasses for 10 years with no problems. I got my prescription updated over a year ago and had no problems, as usual, until about 5 months ago. One night while on the computer I started to feel a little strain like the screen was a little too bright. That had happened in the past very rarely so I didn't think much about it. The next day it got worse and I started having eye pain after about ten minutes of looking at my monitor (keeps in mind I've looked at monitors for hours before with no problems like this). For two weeks, I couldn't stand to look at ANY screens. TV, computer, phone, etc. I had to use my phone and PC occasionally but could only tolerate it when the brightness on these devices was completely turned down. The pain was like having really dry eyes but when I looked at a screen, I could feel a pain shooting through my eyes (mostly my right eye but still in both.) After two weeks, it got a little better and I could look at screens some, but the brightness has to stay low and it still hurts some more days than others. It's been 5 months and it won't go away. I've been using drops for severe dry eyes and it seems to have helped a little but not much.

NOTE: I went to my eye doctor a few days ago. He checked my prescription, focusing range, and looked into my eyes (but he didn't dilate them). He basically said my eyes were perfectly fine and told me to take breaks every once in a while when using a computer and pushed me out the door (in a manner of speaking). I've been taking huge breaks and limited my use to 1-2 hours a day and still I have the same pain.

What should I do? I start college for a tech degree this fall and it hurts to look at screens. I'm in a deep depression now because I can't find relief and I need to know how to fix this. I know there's something wrong with me, I just don't know what. Should I get a second opinion? I've read that if your eyes are really dry or something, you could have a tear or do some kind of damage and need to put antibiotic ointment on your eyelids to help repair them. I don't know if that's true but I friend described my problem to his eye doctor out of state and that's what he said. And I've read it in a few places online. 

It would mean the world to me if anybody would lend their advice. I'm so close to  just giving up and hope I can be happy in another career & routine that doesn't involve as many screens but it's making me miserable.

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