@AbsentmindedWoman
I am in front of a screen all day - the glasses I ordered yesterday have a blue light filter on, might that help? Or can you get something to stick on the computer that helps with that I wonder?
Did wonders for me, did blue light filtering glasses.
I used to suffer similarly to your symptoms and cause, too much screen use. The very first time I put them on, I felt my eyes relax. It felt like putting them in a bath of luke warm water is the only way I can describe it. I still sometimes relapse after I get idle and stop using them but they soon fix it again.
Keep them on when not in front of a screen too, the blue element of artificial light is irritating too and daylight.
From my own experience, I personally think that your eyes can become really sensitive to blue light from many different sources.
Also try taking a break every so often and use cupping.
Hold both hands like you're scooping water and hold gently over your eyes, trying to block out as much light as possible and hold position for a few minutes. I find it helpful to wash my hands in nice warm water first too.
Also, you can try taking a few moments away from a task that is causing you to focus intently on one spot. Pick a few things around the room or outside at a variety of distances. Trace around them with your vision, switch from one to another then back again.
It's surprising just how tense your eyes and eyelids can become. The vast majority of us take them for granted but there are muscles involved just like anywhere else on the body and it can contribute to dry eye in my experience, especially when you have overdone it on the computer or a craft activity.