Thank you for all of your replies and concerns.

To answer all of your questions:
Our puppy's name is Casper. (The vet told us that he is 7lbs. He will be full grown at around 8lbs.) His condition is pretty much the same today. As expected, his shoulder seems very tender. He was on a leash during the walk. I don't know why the doctor prescribed children's Tylenol. He did recommend that we alternate it with the children's Asprin however. Both were prescribed to help minimize his discomfort. According to the vet, both would be easier on his stomach than anything that he could prescribe for animals.

I'll update this post as things develop. Thanks again!