MY GSD Not Gaining Weight. - Page 2

My guess is this person is in India.  Not the USA, so they would not have access to the same foods as we do. 

First, worm the puppy with a wormer specifically made for worming puppies. 

Second, what kind of milk are you feeding the puppy?   Do NOT feed milk that has been cooked/boiled or homogenized.   Raw milk is ok to feed to animals, I feed mine raw goats milk when I can get it (Raw milk does not cause digestive problems like pasturized/homogenized milk does).  The only thing to caution with about raw milk is your puppy can get worms from it.  Freezing the milk and then thawing it before feeding will kill any worms that the milk may have without destroying key nutrients in the milk.   

Third,  Chapati is bread right?  Bread is not appropriate for puppies,  I realize in India many people are vegetarian, but a vegetarian diet is not appropriate for dogs.  Although it is possible for dogs to live on a vegetarian diet they will not thrive well on it.   Are you ok with any kind of meat product?  Even if it's from fish, birds, rats, rabbits,  snakes, lizards?   Your puppy would do much better with some kind of animal protein in it's diet.  Eggs would also be good for it's diet, soft boil the eggs for 5 minutes before feeding it to dogs, the yolk is ok to feed raw but too much raw egg white can damage the coat.  There is a nutrient in egg white that is known to cause brittle hair but it is destroyed when cooked. 

If you cannot feed any animal protein then make a mix of equal parts rice and legumes (Lentils, Chori, Black bean, Red Kidney beans, peas, etc) as this helps provide most essential proteins.  Potatoes and eggplant can also be fed, although eggplant needs to be very well cooked and mashed up as it can be difficult for dogs to digest.  Rice, legumes, potatoes and eggplants should all be well cooked.  Some veggies can be fed to dogs raw, like carrots and green beans.   Paneer, yogurt, curds and butter can be added too to help make it more palatable for the dog. 
The ingredients of most common Indian dishes are ok for dogs to eat, just don't feed them the spices, peppers or onions.

If you feed your pup a vegetarian diet it will not reach it's full physical potential as it would on a diet with meat included.  Vegetarian dogs are prone to infertility issues, female dogs may develope masculine characteristics and male dogs may stay more feminine.  

What are the ingredients in the puppy food that you feed him?  I would continue to feed him the puppy food, particularly if it has animal products in it.

I feed my puppy a bowl of soup (chicken or meat) next to every meal. It is very useful for him and I already noticed a progress in the way my puppy looks.
You can feed him soup as much as you want, but he will urinate more. But I don't mind.

I also noticed a major difference when I started feeding my puppy raw food. I was a little hesitant at first but when I read so much about raw diet for GSDs and I applied the advices given to me, I have become more covinced that raw food is the best for them.