Thanks everyone! I am very glad it wasn't more serious.
Last night he jumped up, because he heard the front door open, and yelped. Poor guy. BUT this morning at 3am he wanted to go outside (which is unusual for him). And when I opened the door he went running, almost like his leg was perfectly fine. But it wasn't, he's still limping. He is improving every day. I think the pain meds are really helping. I just hope they don't help too much and make it more difficult to keep him calm. I guess a few trips outside to potty isn't too much, even if he does run.