Hi, please confirm if your dog is being regularly dewormed. You should never feed "Milk" to dogs because dogs are " Lactose Intolerant" - meaning they cannot digest milk enzymes. Instead of milk, you can feed buttermilk or curd which is very good for their stomach in summers.
You can certainly feed chicken daily to your dog in summers. Makse sure you feed chicken breast not bones. Chicken breast is nothing but muscles and is very rich in protein.
As far as Commercial food is concerned, you can feed the combination of both. You can feed RC in the morning and Home-food in the evening. Apart from chicken, you can feed Butter-milk, curd, roti, bread, vegtables ( without spices ), paneer, eggs, to your dog.
Please make sure your dog is free from parasites like ticks/flees. After consulting your Vet, you can also give him tick-fever vaccination.
Make sure your dog is given fair amount of exercise through short walks, play sessions inside home. This will keep him busy and tired.