A rattling or wheezing sound in a 6-month-old baby is a warning sign that requires immediate medical evaluation. At this age, these symptoms often point to conditions like bronchiolitis or a respiratory infection, which can deteriorate quickly. Please do not try any alternative oral medications without professional guidance. I strongly advise taking your daughter to a pediatrician immediately to check her chest and oxygen levels. The mother should also be evaluated by a physician. Meanwhile, ensure the baby is well-hydrated and use saline nasal drops to help clear any nasal congestion.