Recently I have came across a problem where both my nostrils are completely blocked for long periods of time. I had been using Using Sudafed several times a day, but recently it has suddenly started to become less effective as well. If I go for a run it clears it respectfully well, but about 10 minutes later, both nostrils are completely blocked.

So what is this an infection, flu, cold etc? I personally feel fine everywhere else, other than the nose part.