my baby is 4 month nd 8 days old.. does he need anything else except of breastmilk.. his birthdate is 20 th April 2022.. from last 20th July and this 20 th July he gained 500-600 gm weight.. but from this 2 nd August his weight was 6 kg but 2 days before when I went to doctor for routine checkup his weight was 6.300 ..he gained only 200 -300 gm weight in 25 days..what was the reason.. in this august month he also got vaccinated and then he got fever for 3 days..