Do you need to see a doctor for help getting rid of a postnasal drip?

You may try a couple. Things like sudafed with breakfast and loratidine at bedtime and see what happens. Otherwise, see your doctor if no better.
Postnasal Drip. Every day, glands in the linings of your nose make about a quart of mucus each day. The excess can come out of the nostrils -- that’s a runny nose. When the mucus runs down the back of your nose to your throat, it's called postnasal drip. http://www.webmd.com/allergies/postnasal-drip.