postnasal drip in infant

8.5 mths LO had runny nose since last Monday. At night she don't sleep well because she will choke and cough. It's seems post nasal drip is the culprit that triggers her cough. Day time she is quite alright. Especially when she is lying down, she seems trying swallow down something then gag Abit. Any mummy Lo got similar problem? Went to PD on Thursday, prescribed sterimar hygiene water, iliadin, telfast and cough med to standby if she is coughing very badly. But LO seems not getting better or worse. When she sneezed, thick mucus came out from her nose. She is also teething with her 8th tooth popping out. What other ways can speed up her recovery? Humidifier? Essential oil? Balm to apply? TIA!