你的句子中的 often 是 after 的误拼。

误：Who does often looks after him？

正：Who often looks after him？谁经常照料他？

析：who 作主语时，其后直接跟谓语动词，不用助动词 does, do, did 等。

再如：

Who told you that? 谁告诉你那件事？

Who painted this picture? 这幅画是谁画的？ 

Who owns this house / dog? 谁是这房子 / 狗的主人？

Who sang at the concert last night? 谁在昨晚的音乐会上唱歌了？ 

Who looks after the maintenance of these machines? 谁负责维修这些机器？