I have this problem despite adjusting my monitor height properly.

I consulted a practitioner (in Taiwan, so I'm not exactly sure how to describe her.) She directed me to do the following: stand on tiptoe closely against a flat wall where the ceiling is higher than I can reach on tiptoe. Keep forehead against the wall. Reach upwards, keeping the part of forearms nearest the wrist against the wall. Inhale and exhale, relaxing muscles and stretching to reach further and further upwards with fingertips. Do this for at least 30-45 seconds, relax, repeat a few times daily.

I am not good at sticking to the program but it does seem to be helping

I also suffer from severe tension headaches and go to a chiropractic clinic. I don't fully understand the theory, but they apparently move my spine back into the correct position by gently rocking it. I've been going for about two months now, and I'm gradually getting better. At the clinic, I'm given several types of exercises, mainly focusing on the muscles around the shoulder blades, and I perform these exercises each time until my next appointment.

I did a while ago, first you've gotta fix your setup so the top of the monitor is at eye level. Then do neck bridges; put yourself with your back against the wall, use the back of your head as support and move your body and feet a bit forward while keeping the back of your head as support, keep your neck straight. You'll feel a burn in the back of your neck. The more angle the more the burn.

https://youtu.be/RXhyx-vVG_Y?si=TiQVGASxnIRPQDTl

Do it for 30s, maybe 3 times a day, you can also move your feet forward for more challenge.

Speaking out of my ass: I'd guess your posterior neck muscles grow weak due to the unnatural posture and your frontal/side muscles overpower them. Eitherways, it works.

Three bits of advice from having gone through this:

1. You need both stretches and muscle strengthening exercises.

2. Ergonomics while working matter, things like putting your monitor higher will help a lot compared to hunching over a laptop.

3. Consult a physiotherapist. If money is tight then just do a single visit and ask him/her to diagnose and then give you some tailored exercises. You can then do those and might not have to go back.

I forced myself to evaluate my own posture whenever I get up. This was difficult at first but comes naturally now. No special tools, just making a strong mental note each time I forget. It's not been working perfectly but pretty well.

I'd echo at least seeing a therapist even to get a single diagnosis just to make sure there's nothing more serious going on.

My personal recommendation is to look into the short exercise book "Treat Your Own Neck" by the late physical therapist Robin McKenzie.

Not that I know anything ... but I keep thinking about getting a neck brace and wear it when I work on a computer. Seems like a 'simple' fix ... but I have made that mistake before (as in think it is a simple fix).

surgery-free, ballroom dance teacher fixed mine with insults and side-eye