Messages

Have you tried verifying game integrity? That helped me.

Steam -> Library -> Right-click on Rimworld -> Properties -> Local Files ->
-> Verify Integrity of Game Files...

I'm having the exact same problem. I've played a lot with mods without any problems, including the set of mods currently active. Tried to revert every mod that got updated recently. Also tried to disable suspicious mods. Tried executing all incidents, and altho some of them gave an error (from Cthulhu modpack), they were different and much better explained. I also tried to caravan out and abandon the colony.
No luck so far.

Anything I could do to narrow down the problem?
Even if the savefiles are corrupted beyond recovery I would like to know more about the problem.

Prioritize bleeding wounds, and/or allow manual priorities during treatment.

At the moment it's not even random, but it seems like doctors are programmed explicitly to heal wounds of missing limbs LAST, then other major bleeds, then small bleeds, and everything else that cannot affect immediate survival like burns and bruises are treated first.