ToME: the Tales of Maj'Eyal

After my last boss fight in the east, my character's health regeneration went from +.06ish to -1.89 permanently. He can't rest anymore because of the constant damage and only stays alive by repeated healing. I've tried removing and re-adding gear but it doesn't change. This seems like a bug. Does anyone know a fix to reset the health regen to something normal?

Thanks!

Check your inventory for a suspicious rock