I am a couple of weeks into a new job. I had only started the previous new job in June, but after a week where I was in tears twice in a week, I knew I had to look elsewhere. The stars aligned for me - new new job is fewer hours, substantially more money and closer to home. And so far, without any micromanaging arseholes, but it's a large organisation, so I'm not daft enough to think there are none.
There are positives. If he's still in his probation period, that would imply his CV etc is up to date. It could also be he has a shorter notice period, (I did take a little pleasure in giving only a week's notice, if I am honest,) though that depends on his contract.
If he can get signed off - and losing 10lb in 2 weeks should persuade any GP - with the upcoming Bank Holidays as well, he should get a break. The jobs market does stall over Christmas, but should get going in January, people back in the office, new projects, new budgets. People have posted about options around mortgage payments and benefits and so on.
It's horrible to have to go through this, but all is not lost. Good luck to you both.