I have itchy palate nose n ear. Phlegm was removed from my right max. Sinus 3 years back. Is this is due to sinusitis or any other reason?

ENT consult. It may still be a sinus problem, please see an ENT surgeon. Nasal Allergies may also be a contributory factor.
Allergies? Symptoms could be due to allergic rhinitis or chronic sinusitis. Itching points to allergic cause, but allergies that are untreated may increase risk for sinus infections.
Seasonal allergy. You have an itchy palate. You may be experiencing seasonal allergies. Try taking over the counter nasocort. Of it gets better after one week then you have your answer. If it gets worse then see your doctor.