Ah, I just checked the required materials in the save data,
the last one is just a normal health potion (:
I think it would have been fine if you had Bandages + AntiBreeding Ointment + Spectrum + HealhPotion in your inventory. After that, I think that if you kill time by repeating sleep and waking up until the morning for a few days, and talking with Tank, Scar will recover. I think it's a good idea to save once you have all the materials just in case.