Hi My 3 Week Old Baby Has Had A Respiratory

Hi my 3 week old baby has had a respiratory infection for a week now. She can breathe OK in the day but at night time she is severely congested and is struggling to breathe when she's awake. I have tried saline drops, a nasal aspirator, a dehumidifier in our room, steaming water, raising the cot. Everything we can think of doesn't seem to make any difference. The doctor has just prescribed vistamethasone drops but I'm unsure whether to use them as it says for redness or swelling on the instructions not congestion. Also my husbands friend who is a doctor recommended paediatric otravine. What do you suggest?