I'm thinking that your cold has developed into a sinus infection which can be very dangerous if not treated , My advice would be to seek medical attention as soon as possible so you can get an antibiotic started .
Im sorry to hear you are so sick! I have never had a cold last that long. I would be seen if I had the pressure because it could be a sinus infection, and those can become dangerous if it just festers.Get better soon!
I would have your doctor order you a CT of your sinuses you might have a chronic sinuses infection that isnt clearing with antibiotic treatment. You also might be developing some allergies which will cause the nasal drainage etc. Hope this helps