An over-the-counter, non-steroidal anti-inflammatory drug like Advil or Aleve would be effective against sore throat. Cepacol Lozenges for sore throat arising from Post Nasal Drip are also good, and so are Chloraseptic Relief Strips. Talk to a doctor for medical advice.
You could try getting some Chloraseptic (sp.?) Spray. I've used it w/ strep throat & it works really well. You spray some onto the back of your throat & it gets numb for a while... feels a LOT better. It's available OTC at pharmacies, discount or grocery stores, or wherever you buy cold medicines. Get well soon! :)
Have you tried a saline nasal spray? Or recently became OTC, Nasal Crom nasal spray. They should slow down the post nasal drip. Also sleeping with a humidifier may help. If all of this fails see an allergist or ear nose and throat DR.