Since she is only three and a half months old and has been coughing for over a week, it is very important not to start any new medications without a doctor's guidance. While the chlorpheniramine and phenylephrine in Sinarest AF helped her runny nose, and ambroxol in Mucolite was used, persistent coughing in young infants needs a physical exam. Please have her evaluated by a pediatrician. They can listen to her chest to ensure her lungs are clear and recommend the safest treatment. In the meantime, keeping her well-hydrated and using saline nasal drops can help her feel more comfortable.