This is a psychological issue, but everything psychological is also physical. It’s all one interconnected system. So please see a doctor and have your bloodwork done. Doing that was the first step to escaping my burnout. I wish I had done it sooner.
These are all good things to have done, but the secret hope of everyone once they walk into the doctor's office is to get told "take this drug and you'll be back to feeling like you're 24 and just graduated college".
You really have to insist, in the US anyway, that there is really something wrong. I was told for ~6 years "idk you're depressed bro", when in fact there were material physiological things that could have been addressed right away.
The fear of this attitude, which is all too common, is what keeps me away from doctors.
I had a doctor several years ago who was amazing. She actually focused on lifestyle and would even host classes for her patients at night. Best doctor I ever had. Sadly I moved away, and I don’t know how to find another doctor like that. She was like a unicorn.