Was with a corpse, standing in waist high water, and the message said, at least I think, that I had to rest before being able to move. So I had to rest under water oddly enough, since moving to the side out of the water wasn't possible due to being stuck. Icly, it didn't make sense that without any warning you can't move. I'm sure a point comes where one can't move, but you sense it coming with fatigue, and in that situation in the scrag cave, icly Nell would have dragged the corpse out of the water to the ledge, but was forced to rest in the water so as to then move.
Just a wierd a situation.