Welcome to the board.
If the dog is 1 month old -- four weeks, there are some real concerns and the sooner you can address them the better.
Why did your friend give you a pup this young? It should have another month with its litter. Even if it is totally weaned at four weeks, which is doubtful, or if the dam passed on, it still should be with the other pups for the interaction with puppies its own size and power level.
Right now your pup is very susceptible to every disease out there, needs careful feeding, worming, and special interaction to prevent problems with bite inhibition.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC