I don't know. And how should i clear it?

There isn't sufficient information to reach a specific diagnosis. I would advise you to visit the ER so that you can be evaluated and undergo the necessary investigations to find the underlying cause and have it treated accordingly. These following steps may help: - Avoid cold food and water, preferably have hot food and water - Don't skip meals have a liquid diet containing soups and progressively increase to solid diet as per how you can tolerate. - Have food rich in vitamin C such as oranges to help build immunity. - Drink plenty of fluids, drink 3 liters of water per day - Do salt water gargling with lukewarm water thrice a day - Do steam inhalation (plain steam) thrice a day and apply vaporub over your chest and nose - Maintain good personal hygiene - Rest plenty, body heals while at rest