toothache不是可数名词，因为toothache指病状为抽象名词所以为不可数名词，中文意思是n,牙痛She had toothache all day.她牙疼一整天了。

I've got toothache.Do you often have a toothache 你经常牙痛吗？I have a terrible toothache.我的牙疼的很厉害。