This is not a medical advice. And if you experience burnouts returning frequently, that‘s what you might wanna get.
However, I noticed, when I started to work in a regular job, I was able to work all year without the need of taking time off. I was used to it, since I was self-employed before that. After the first few years at this new job I started to feel the same things you‘ve felt (but maybe not to the extremes you‘ve described). So (with the lovely advice from my SO), I decided to take all my accumulated time off and we went to a place, where I really was able to turn off my phone, let my mind wander and together we explored new things. After 3 weeks, I felt not burned out anymore and was able to perform.
This lasted for about 5 months after which I took another vacation. Now I try to take at least a week off each quarter. With a longer vacation once a year if time allows.
So, what I want to say: take time off where you can stop thinking about your occupation (and anything like social media or emails). Try to learn something new (if you want to be productive) that isn‘t tied to goals or deadlines (and don‘t try to make this new hobby a profession) or you will find yourself in a worse cycle with two jobs. Even better, immerse yourself in something unproductive.
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