IANAD, but sounds like a potential ADHD case:
https://en.wikipedia.org/wiki/Attention_deficit_hyperactivit...
https://en.wikipedia.org/wiki/Attention_deficit_hyperactivit...
Just be aware that this might be your problem and if it is, medication might do wonders. I'm not saying to jump on that conclusion but make sure you explore it.
If it feels like you just can't get your brain in first gear to start the work, if it feels like you're an old steam locomotive slowly starting to get moving and it takes enormous effort to do it.
The worst part apparently is a mix of high IQ and ADHD which causes people to get a diagnostic at a late age. (early to late twenties or later).
Accepting that I had ADHD was a blessing. I finally stopped walking around with bruises on my legs from not completely clearing my furniture
Still, ADHD can cause hyperfocusing, and if he is hyperfocusing on the Anxiety side of not getting things done, medication will only partially help. He'll need therapy/other techniques to get over that hump
OP indicated that this was a recent trend, which would cast doubt on the ADHD explanation. Not that it's impossible. Maybe OP cut their coffee intake in the past year, or maybe some recent event sent them spiraling into a depressive loop. There are a number of ways that previously controlled ADHD symptoms can suddenly run wild.