Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry for this concern for your cat. I do have a few additional questions to ask about him first if you don't mind:
1. How long has his leg been like this?
2. Is he eating and drinking?
3. Is he excessively vocalizing or meowing when he walks on his other three legs?
There may be a slight delay after I receive your answers since I have to type up a response to you. Thanks for your patience. Deb
Thanks for the answers to my questions and the additional information.
It's certainly possible that he has sustained a fracture but it's equally possible that he's developed an abscess or infection. Since it doesn't sound as if he's in great distress, you probably can wait until tomorrow to have him seen. I don't want to minimize what may be going on with him but cats are pretty amazing when it comes to handling injuries to their bodies.
If you decide to wait, just make sure he's isolated in a space where he can't further injure himself such as a small bedroom or bathroom.
I wouldn't advise any over the counter medications such as Aspirin (as I would for a dog), since cats are overly sensitive to many of these products which might cause more harm...the last thing we'd want.
If the injury appears to be localized to his foot/paw, then you could soak it for 5-10 minutes (if he'll let you, that is) in a warm Epsom Salt bath which may be soothing.
I hope this helps and that nothing too serious is going on with him. Deb
You're more than welcome and thanks for the rating; it's greatly appreciated/
Best of luck with your cat. Kind regards, Deb