Hi.. Thanks for the query.. Your symptoms are clearly pointing towards fungal infection in mouth and the white coating is due to yeast/fungal growth over the tongue.. The condition is known as Oral Thrush. The inflammation over the roof of the mouth is also due to infection.. As you are a smoker, thrush is common and if you continue to smoke it can also worsen the infection.. So first of all you should quit smoking. In case if you are addicted you can go for nictotine replacement therapy in the form of nicotine patches and gums.. Fir thrush you can gargle with specialised mouthwash like Nystatin mouthwash that is an antifungal composition.. Suck Clotrimazole lozenges. You can also be advised oral antifungal medicines like Flucomazole.. Drink plenty of water.. Clean your tongue daily with a tongue cleaner. Eat plenty of probiotics like Yogurt and garlic as they are helpful and clearing infection faster.. Hope this helps.. Regards.