[Chance]

i think that as is the system is either too punishing or not at all, where rolling a 1 / getting a perm sucks a lot but a temp does not hinder or really matter in the grand scheme of things. there's too much RNG involved; if you have three+ perms, it's purely because of bad luck

instead, perhaps something like:

• temp injuries cannot be fully healed. you can halve the -vit with medic or a potion. tone them back to -10vit
  after a temp injury expires, it becomes a 0 vit perm injury, a 'scar'. cute reference/memory
  
• your first perm should be -10vit (-5 when healed). each one afterwards should be -5 (-2.5 when healed). the stacking/bad luck factor would be much less punishing then