Yeah, I just got this game and wasn't sure what to do when a character is simply weakened. His health bar is low, so I figured I may be able to heal him somehow.

What confused me was a part of a guide here: Villagers who show a status of "Weakened" will generally improve in health over time unless they are sick, elderly or continue to suffer injuries.

It also mentions prolonged disease. I'm not sure if he is weakened because of the mushroom (After I healed him, his health was still pretty low) and if he's just going to die or what. His health has just been getting lower, not improving.