Supplement for my gsd puppy??

Hai, my two month old gsd puppy is scratching, itching, recently got hair loss in small patch on its face above eyes, got hair loss round the ears where it scratches usually and also lost hair on its body in small patches, I took it to vet, He gave a neomac injection and said it got dermatitis and refered another dosage of same after 5 days, Please guide me about his skin problem, he is also having small little bumps under his chest and abdomen. Is this only dermatitis ? I made grinded paste of boiled beef, chicken, spinach, carrot and serve it daily, I give it calcimist pet, prooviboost syrup and nutricoat advance supplements daily ? Advise me what can I do further ? All suggestions are appreciable, Thank You