He is underweight for his age. You did not state his height so I am unable to assess his height for his age. A 22 month old child should be eating 3 meals a day with snacks between meals. Suggest giving him Pedisure instead of
milkBreast milk
Breast milk jaundice
Lactose intolerance
Nipple discharge - abnormal for additional calories and nutrients. Try to give him yogurts, cheese, puddings, and ice cream for snacks which are higher nutrient / calorie dense foods to help with weight gain. Hope this helped.