I haven't had it with chickens yet but several of the ducks have developed limps at various times. Mostly they recover within a couple of days on their own but if they don't, I do just what the others have suggested and isolate them with food and water close at hand. One young duck needed vet treatment and after no response to anti-inflammatories, it turned out to be an infection and she improved within hours of starting on antibiotics (making catching her to finish the treatment hard). I've got a collapsed duck in the kitchen at the moment with her food and drink close at hand but I think she may be close to the end of her days (probably slightly more than the 2 1/2 years I was told when I got her last year). The vets always check closely for bumblefoot as their first port of call, then for any signs of damage higher up but if she can put weight on that leg, it's a good sign.
H