My hen that I lost was like that - could not bear weight on one leg. Post mortem I found a deep cut right between her legs in a location that was very difficult to see. I had wrongly attributed her lameness to her other wounds. Have you tried wrapping her in a towel, rolling her over, and taking a *very* thorough look? I thought I had checked my hen over well enough, but I hadn't. It's very difficult to see a gash in that area, especially if she's heavily feathered as mine was.