My boy is 10 month completed. During birth he had Jaundice and at 1st month UTI infection cured and weight reduc . Still he is not sit without support. he can sit with support sometime and he have head lag issue (front to backward). And not gaining weight (now 7.3 kg & BW is 3.2 kg). So we consulted doctor and took blood test and mri brain spine. As per report (prominent subarachnoid space) and blood test are normal. Doctor said blood tests, newborn TSH are normal. MRI spine and brain is normal with prominent subarachnoid space. we provide vitamins, calcium and iron drops. Baby also eat and sleep well. But why my baby not sit and not gain weight. Please help me what I need to do now.