I've had far more problems with lame ducks than any other health issues in any of the animals. I normally leave them for a couple of days to see if they pick up unless they are so bad, they can't get to the food and water. Most of them limp for a couple of days and then pick up again. If they're too bad, I've taken them to the vet. Then they get anti-inflammatories as a first course. In two cases, they've then needed antibiotics and with one that cleared it up - it was infected at the knee joint. I've one currently that has a suspected broken hip so we've tried him on a course of antibiotics and anti-inflammatories just to be sure. He's still not back on his feet although he is perkier and I'll not be paying for X-rays etc. so I think I'll have to cull him but I'm just giving him a week or two to find out whether he can find a way of getting around again.
So I'd suggest leave them isolated close to food and water for a couple of days and check whether the rest helps. If it doesn't you'll have to make a call about whether to pay for the vet or not - you might be able to get anti-inflammatories on line but no idea how.