Update

We never ended up taking Joe to the vet, it took a couple of days for him to recover though. He was up and moving around the next day, but he seemed to never be comfortable and not as responsive to certain stimuli as usual. He didn't "talk" much either. He usually has these little yips and growls that he uses to communicate. We think maybe his vocal cords were injured in the fall. He was on his leash when he jumped out the window, so when the leash went taut it may have bruised the vocal cords. So for a few days he was very subdued. But it seems that he has made a full recovery. He is just a yippy and active as he ever was. We're glad to have our 'old' Joe back.