The Nasacort and saline may help with the postnasal drip by reducing any inflammation in your sinuses and helping to rinse out any secretions and keep the passages moist.

If you have any symptoms of GERD it is more likely that's what's causing your symptoms. The sore throat and post nasal drip are very common symptoms of GERD and if you get the GERD under control (with something like Prilosec OTC) you should start to notice an improvement in your symptoms in a few days.