Step 1 is to ask for a referral to a doggy dermotologist.

Step 2 is to ask the doggy dermotologist if your puppy has Pemphigus which is an auto-immune disease of the skin.

The usual first try for treatment is large doses of Prednisone to suppress the immune system, and along with antibiotics attempt to get the skin to heal. If Prednisone doesn't work, then more potent immuno-suppressent drugs are used.

The doggy dermotologist will want to send a biopsy of the skin off to a Pathology lab that has the expertise to diagnose skin diseases. While waiting on a diagnosis starting on Prednisone, and antibiotics could be a worthwhile thing to do.