Which Specialist Should Be Consulted For Sore Throat And Productive Cough?

I started having symptoms on 10/4 - nasal congestion, sore throat, cough and fatigue. I saw my PC on 10/11 and he felt we should wait a few days to treat. On 10/13 he prescribed 7 says of amoxicillan. There was no improvement. On 10/19 he prescribed cefdiner (or something like that). There was a slight improvement in congestion but the cough worsened so that even with an expectorant it hurt quite a bit to cough and I was making funny noises when taking a moderate breath. I went to a same-day clinic as my PC was closed. They took a chest x-ray which did not show pneumonia on 10/27. They prescribed 5 days of prednisone. There was no improvement on the 31st my PC prescribed a proair inhaler to be used as needed every 6 hours. While I do have allergies, I have never had asthma. Again, there is little improvement. I now have soreness in my mid back on my right side and *inside* rather than surface. Whenever I shift position I cough, I have a very sore throat and cannot lie down to sleep due to coughing. The mucus I am coughing up is grey-green and firm rather than the usual consistency. I am at a loss as to who to see at this point. I feel that continuing much longer as is will drive me to tears. Do you have any suggestions as to where I should turn to find out what is going on?