Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain it seems that yellow coating on the tongue can be due to either deposition of debris and dead cells over the tongue papillae leading to yellowish appearance while in case if it is in the form of cheesy white-yellow patches it can be due to yeast infection known as Oral Thrush secondary to dry mouth that is commonly seen in smokers.. Enlarged uvula seems to be due to inflammation caused due to heavy smoking of Marijuana and cessation of habit and warm saline gargles will help to resolve it.. You need to consult an Oral Physician and get evaluated and in case if it is just due to debris deposition maintaining a good oral hygiene and cleaning the tongue regularly using a tongue scraper can help.. Gargle with 1:1 solution of hydrogen peroxide and water will help.. You can also dip a soft tooth brush in this solution and gently clean the tongue.. But in case if it is thrush antifungal mouthwash like Nystatin mouthwash, clotrimazole lozenges and taking plenty of probiotics like Yoghurt and garlic can help.. Drink plenty of water and maintain a good oral hygiene.. Cessation of all kind of smoking and recreational drugs is must.. Hope this information helps.. Thanks and regards. Dr. Honey Nandwani Arora.