I think I found out about (one of) my problems. During this Windows upgrade, I was going through a stressful moment in my daily life and I felt my TMJ disorder getting way worse. I kept on using my computer (with build 1803) with mild strain. I decided to use my dental protector at night as I haven't used it so much, and tried some stuff to relax during the day.
I can totally use my computer again, as before...
So I can fairly say I found some of my triggers, stress and TMJ disorder. Maybe it prevents my eyes from working well or being aligned.
Thanks to all for listening and helping
PS : It doesn't solve my problem with all the screens though, just some that suddenly became unusable.