No, the implications was that both him and the girl were in the dungeon for 2 months. We see them hunting for a bit in the last chapter, didn't we?
I don't think so. Unless there's a translation error, Erin said "It'd been 2 months since the last time I saw you" on page 6. The last time she saw him was page 13 of the previous chapter, when he had her escape the dungeon and he stayed behind on that 20th floor to fight the midboss. She also says it took them that long to get that deep into the dungeon. So, either he spent 2 months fighting, or the fight was short and he passed out and was retrieved 2 months later, somehow alive. He says he slept for a whole day, though, so I guess we're meant to believe he fought for those 2 months.