Raoulas
My advice would be, if you can, to actually avoid screens at least for some period of time. So that you can let your body recover and then when coming back using screens, you can notice with more precision what triggers you and how and can decide then if you need to definitively stop using them or can find an alternative.
Your body is giving you symptoms of pain and discomfort and you should listen to them. It can be hard to avoid screens and the consequences are not easy to deal with for sure, but your health and your body matter the most, you will thank yourself later if you care for yourself now.
Personally, I can only use old phones, but even them are problematic for me and I keep them switched off most of the day. People can't join me most of the time, I use the phone maybe 30 minutes a day at max but at least I feel free and at peace. It costs me a lot but peace has no price for me (i can understand there is a limit though).
As for pc, I have the luck to not be as sensitive as you possibly so I can still use them when I need them.
To sum it up, my best advice would be to try 2 weeks or so with 0 screen usage and i mean 0. Maybe travel somewhere to reconnect to life a bit. Give your whole system a true rest so that it recovers a bit. I've personally done that and it's incredible to see how people are addicted to their phones. If you sit in a café, you'll notice EVERYONE is using their phones even if they are in groups.
After you come back after this rest, you will have clearer ideas and then you can may be come up with strategies on how and when to use screens.