There are a couple of possibilities here.
The first is that you were using a nasal spray containing a strong decongestant element (such as Afrin, or its generic equivalent oxymetazoline). These decongestants have a very peculiar effect on the linings of the nasal passages. If they are used for a day or two, they are very helpful in reducing congestion. However, if they are used for much longer than that, they actually provoke 'rebound' congestion, which is often much worse than the original congestion. Therefore, if the product you were using was one of these, it is very likely that your worsening congestion is due to overuse of the spray, and you should discontinue it immediately.
The other possibility is that your upper respiratory infection has progressed to full on sinus congestion or sinus infection, which would explain the worsening pressure.
I would recommend that you go to see your primary care doctor
about this issue as soon as possible. They will be able to examine you for signs of sinus infection and help you determine whether this could potentially just be a side effect of overusing nasal spray. Based on what they discover, they will recommend a new treatment to get you feeling better.