Sensitivity can be initiated when there is exposure if the Inner Dentin layer when enamel is worn off or gums recede or there is decay in enamel. Sensitivity pain can be initiated on consuming sweet, cold, blow of air. Your problem could be because of wearing away of enamel or gum recession. Sensitivity will not cause any pyorrhoea or gum disease

Visit your Dentist regularly and get prophylaxis twice a year

Sensitivity can occur due to many reasons ranging from gum recession, erosion/ abrasion of enamel due to hard brushing or even cavities. The exact cause of sensitivity for you can be diagnosed after clinical examination. Consult a dentist for proper treatment