What Causes Chills And Cold Sweats While Recovering From Nasal Congestion?

I have had congestion now for about 2 months. I am prescribed Claritin D and Nasonex. My nose is pretty cleared up except for I still have post Nasal drip which created mucus. This isnt that bad, but i suffer from chills on an almost every day basis without ever having a fever. Sometimes these chills are accompanied by a coldsweat. These chills can last anywhere from 5 minutes to an entire day. Any ideas on why? Thanks