Found: Short story - man recovering in hospital dreams of concentration camp

Short story I read in a collection.
I think the name of it was "Camps." But I'm not sure on that.
A man is in hospital, recovering from something. He speaks to someone -- either a nurse or soldier that liberated a concentration camp, or someone that survived camp -- who shows him a picture of three survivors taken on the day the camp was liberated.
In his fever/pain/recovery, he dreams of two doors. He enters one door (and later the other) and dreams he is in that camp. One of his friends he recognizes from the photo. There's a term used in the camp for those who have lost all hope and practically the will to live: "Muselmann." In another dream-trip to the camp, the narrator sees a muselmann collapse, near death. Recognizing him as another man from the photo, the narrator saves him, even though his friends tell him it's a waste of effort.
The story progresses and the camp is liberated by Allied forces, and one of the soldiers takes a picture of the narrator posed between his two friends.
When he awakes, back in his proper modern body, he asks the owner of the photograph to see it again. The story ends with him noting that the man in the middle looks nothing like himself.

I would really enjoy reading this story again, if anyone knows it.
Thanks!

EDIT: Solved!

Yep! The story is called "Camps". It may have appeared elsewhere, but I have it in the book More Wandering Stars.

Thank you! Now that I have the author to dig with, I actually encountered it in The Arbor House Treasury of Horror and the Supernatural
Which I own, so now I can read it again.
Thanks again!