Monte I'm the same as you where I have a dual issue and have since 2011/2012:
Issue #1: Severe sensitivity to LED light or backlights
Solution #1: Total avoidance of LED lighting.
Not the best solution, but I haven't really found anything else yet. Even blue-blockers don't seem like enough, however, I haven't tried some of the more aggressive orange-tinted glasses some have recommended (I think they are called SCT or something?)
Issue #2; Aching eyeballs from reading overuse
Solution #2: Breaks (20/20/20), vision therapy, enlarging print where possible
I did vision therapy for multiple years through my optometrist. It involved in-office visits every 2 weeks and home exercises a good 5x per week. I eventually "graduated" from vision therapy when I was able to basically do pencil pushups to my nose without losing convergence and getting acceptable results on the accommodation tests using the prisms. My vision therapist said that while I can do OK with keeping the pencil fused to a close viewing distance, the key is to hold that fusion comfortably for long reading sessions.
I also have had a lot of relief from just simply using the computer less (surprise, surprise!) I bought my first house a couple of years ago and I have a lot more things I need to take care of and do around the place for upkeep and what not. I've even managed to take up a weird enjoyment in yard work (it's different when it's your yard and there's nobody else that's going to look after it!) This has all helped my issue of having strained eyes and an ache head at almost all times.
My occupation is as a Server Administrator (SysAdmin), which involves a lot of typing and screen-staring. I would always notice the issue a lot worse when I'm doing a lot of close work in spreadsheets, looking at (rather crude-looking and formatted) server logs, and on applications or websites where I'm unable to enlarge the text using Control + mousewheel.
When I'm tired or have read for a while, I can sometimes feel myself lose convergence for a split-second. It's one of the weirdest feelings in the world. It feels like one or both or your eyes have darted to an extreme corner of your eye sockets only to return back to neutral seemingly instantly. That's when I know it's time for a distance-viewing break!
I think they key is to recognize you're getting a strain developing before it happens. It's like holding a plank - it seems easy at first, then all of a sudden, your abs start burning like crazy and you seemingly can't tolerate it for more than a few more seconds!
My vision therapy exercises on weekend days involve tracking the eraser of an HB pencil while doing a whole bunch of motions with it, then doing pencil pushups, then doing a lot of "jumps" (looking and focusing on something really close, then really far, then close, then far, etc). I should also buy myself a Brock String and incorporate it into my "maintenance" vision therapy which I've done for years. There's also probably some good resources online.
It's important not to lose hope. Success stories are out there (although I don't see as many around here as I'd like to!)