2 Months, Old Kitten doesn't eat dry or wet food

We have a 2 months old kitten living in our house with his mother. The cat was originally a stray cat and gave birth. All kittens, are eating canned dry and wet food. But this one kitten doesn't eat anything except boiled egg and boiled and her mother's milk.
I don't know how make him eat other food than that. I am concerned for his health as he is not getting all nutrition.
Please advise what should I do?