I would suggest you take the puppy to your vet and find out what is really wrong with his leg instead of taking her word that she 'thinks' it happened at birth. He is TINY and who knows if he has luxating patella or something funky with his actual bones. I would just make sure that whatever is wrong with his leg is not serious and won't cause you financial stress and heartache emotionally if it cannot be fixed or he suffers with it.
Its probably a good idea to leave him with his mom for another 2 weeks also, until he is at least 12 weeks old. I don't see anything wrong with a 10 week puppy coming home (some insist 12 weeks at minimum) but when they are THAT small, its more beneficial for them to stay with thier mom as long as possible.
Good Luck!!
