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Your sinus could be the prime cause of your breathing difficulty. When the nose and the paranasal sinuses
are congested and blocked then an individual starts breathing through the mouth. This is further worsened by the exercises. I would suggest you to use saline nasal spray
, do steam inhalation and drink plenty of warm water to keep yourself hydrated. If the symptoms do not improve you will have to consult a good ENT specialist
for the thorough examination of the nose and the paranasal sinuses.
Wish you good health