I was a contractor for a few years, and moved from development to DevOps. I think the changes helped delay or hide the issues. I got to the point that I couldn’t manage a six month contract without feeling drained and overwhelmed.
Not to say this happens to everyone but for me it turned into a bad depression that I’m still working through now and I really struggle with severe anxiety. I was fortunate that I could take some time out of work to focus on getting better. I didn’t work at all for over a year.
I joined my wife’s accountancy practice at the beginning of this year and finding ways to improve processes and introduce automation was a gradual way to find something to focus on. That lead to building a SaaS for the industry that has given me something I enjoy working on and which I feel proud to have made.
There are still lots of days where I don’t have the mental energy to work on anything challenging, how you describe feeling after a day of work. I’m having to do what I can based on what is manageable at the time.
Sorry to hear you’re in this difficult place. I can only recommend you listen to your body and try to find a way to understand and work through these feelings. For me it’s therapy but you may have other options available to you.