Hello and hope you are doing well.
It may not be related, sinusitis and dizziness. Your symptom of dizziness if it is relieved by eating something, indicate that you might be having episodes of hypoglycemia. Inadequate sleep can also cause tiredness, fatigue and dizziness. Other causes for this symptom are inner ear infections; brain disorders heart problems, fever, stress, low blood pressure and anxiety. Please consult your GP who will examine you and may ask for blood tests for evaluating blood sugar and CBC.
Hope this helped and do keep us posted.