Two Steps Forward, One Step Back?

Riley had rough night last night. After being in the crate for about 1 1/2 hours, Riley came downstairs about 7:00pm and seemed to be OK. Then for no apparent reason, he started holding his leg up, and sitting in a funny position. He kept going back after his leg so I knew he was in pain. I gave him a pain pill ( the pill before had worn off about 3 hours before this). He stayed pretty quiet until a little later in the night. I was up in the kitchen and Riley was downstairs when all of a sudden he let out a loud YELP!. I ran down and he was sitting down panting and looking pretty distressed. Since I didn't see what happened it was hard to know what caused his pain. I called the Vet this morning and they suggested I bring him in which I did this afternoon. I was worried that he had somehow popped his knee cap out of place. The Vet felt his knee and leg then had Riley walk. He couldn't find anything significant or any damage to the surgery site. He said it could be that he moved a certain way which caused him a great deal of pain. I brought him home and he has been sleeping for about an hour now. He is scheduled to get his stitches out on Monday so will talk to the other vet then if I feel there is a problem. So I will continue our daily routine and hope that he has no more episodes of pain like that. The cold air is here YUCK!!! See Ya tomorrow.