This is ABSOLUTELY NOT normal. Your pup needs to be seen by a vet immediately. An eight foot fall for a puppy eight weeks old is like a human falling off a five story building into the water. The "bump" you are seeing could be from seveal things. It could be from something as easy to repair as a hernia to internal bleeding and the blood is pooling under his skin in his belly area. If your regular vet will not get out of bed find an emergency clinic and take him in right away. This puppy needs to be seen to rule out the possibility of internal injuries.
I hope this helps. Please let me know if you need further info.
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