I can't diagnose you with anything other than massive gay but please do visit a doctor. Brought to you by nurse gang.
No joke but as John Daymon said it could be Diabetes type 2 depending on your life style and other factors. One of the symptoms are dehydration and a more than usual trip to the toilet. There are like 200 types of headaches or more so who knows wtf is wrong. Take a break from Teamfight Tactics nerd.
Learn the most common symptoms of type 2 diabetes — such as increased thirst, urinary frequency, yeast infections, and blurred vision — to help you and your doctor diagnose diabetes early.
yeah its probably migraine it can cause symptoms like that and headaches behind eyes and forehead are typical for it and all the symptoms should be gone the day after unless it pops up again
if u had migraine once ur gonna have it more than once which is very sad maybe the day after, maybe a month after it's different for everyone
migraine mostly pops up multiple times at random in your life without a cause, it's in your genes and probably got it from your parents so staring at your screen in a dark room doesnt really matter, it's the fact when you have migraine you'll be having a hard time looking at the screen because of the aura and the headache
Without knowing your age, fam hx and personal hx, or talking to you I would totally err on the side of caution here. If you are very thirsty it could be a lot of things from a simple cold to as @John Daymon says, diabetes. I wouldn't wait for it to happen again to see a doctor and would probably stop by a quick care clinic in the next week for at least a simple blood and urine test which can rule out a lot of things.
Tl;dr; go to the doc soon don't wait around. This is something you wanna play safe