But how did the doctor know where his house is? Don't you think that's suspicious?

i lowk agree ...

I think he led the way but he's hallucinating or having some memory lapses due to trauma.

I don't think so cuz he was behind the doc all the way there. And the doc announced they were "already there" while he was hyperventilating. I think it's impossible for the doc to know that for sure if he hadn't been there before, especially since almost every infrastructure there has collapsed.