I have a scratchy throat with slight burning sensation in the chest and a nose congestion. what could that be?

Several causes: Your symptoms are very common, so likely a common cause: allergic rhinitis, non allergic rhinitis, gastric reflux or start of a mild viral infection. Call your Dr if symptoms worsen (such as fever, cough or shortness of breath) otherwise continue to monitor your symptoms. Drink plenty of fluids, and avoid foods that could trigger heartburn to help rule out possible causes.