I Have Had A Cold For Two Weeks Actually Since

I have had a cold for two weeks actually since before christmas with a break of 3 or 4 days....now coughing and major sore throat....phlegm is thick and yellow/green. Low grade fever. Just forcing fluids, using netty pot for sinuses, vitamin C...but don't seem to be getting better. Have missed 4 days of work during this time. Taking cough suppressant at night for last 3 nights so I can sleep but nothing during the day - nothing working for the throat. At first I thought it was due to cough and sinus drainage but it keeps getting worse....