What is the best way to help my cat?

My 5 month old cat over extended his leg a few days ago. (I just now got my husband to look and diagnose him tonight) Probibly from playing too rough with my 9 week old kitten or from jumping off the bed. (We used to have a mattress on the floor.) His hind legs wobble a bit when he tries to walk too fast. What is the best way to help him get over this? I know he needs to be confined to a small space so as to use the leg as little as possible, but where is the best place to put him? Right now, i've got him in a pet taxi, but would a cage or a small room be better? And are there any other ways I can make him feel a bit better while he's healing?