rescue sav update

[matmq]

I know that there is no way for you to definately be able to tell me what is up with this sav but any oppinion is welcomed.
In short I got a rescue sav over the weekend and then noticed yesterday it had a swollen back leg (I assumed it was broken) and after i managed to contact the owners i was told it had been like this for 10-15 days when it arrived it wouldn't eat or drink but this afternoon it ate and drank but i have just checked him and changed water e.t.c and he appears to be going lame in his back legs and now both have swollen, before you say it, i have him booked in a vets but he can't be seen till thursday and i have rang all the other vets in my area and none will take him.
Anybody got a clue as to what this could be??