My son is 3 years old. His skin color is very bright. His weight is 12 kg. His weight gaining speed is very slow. All his class mates are of 14 kg or more. HB is 11.4. His skin is also very soft, just the same as of a six month baby. His birth weight was 3 kg. At 1 year age his weight was 9.5 kg. Since then the weight gain is slow. His hight is ok but weight is not increasing. On recommendation of a doc we are giving him 600iu of vit d for past six months. In diet we give one chapati two times a day. Milk two times and little bit of fruit two times. Please suggest tonic etc to increase his weight and mature his skin according to age.. Thank you