[Spoiler] What happened to William after...

[...he, Dolores, and Bernard converge at the Forge? William's gun explodes, Dolores goes inside with Bernard, Bernard leaves, and the next time we see William, it's in the two week later timeline, he's being helped by medics, and he is still alive. Any idea of what he did for two weeks? How he could have survived that? I've been wracking my brain, and I can't figure it out.]