It doesn't seem that a sinus infection you experienced can cause dizziness two weeks later. Sinus infections can create discomfort, especially due to accompanying headaches and a sensation of fullness at the front of the head... but it can’t cause dizziness (unstable body balance). You can visit your GP who can check your blood pressure, administer a physical examination and take standard blood analyses. These tests can help diagnose the cause of your dizziness.