Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concern... As per your complain the smooth red patch over the tongue is due to loss of small projections over the tongue known as Papilla which contains taste buds and due to loss of papilla there is smooth appearance of the area of the tongue and the condition is known as Geographic tongue.. These smooth patches can be seen at different areas of the tongue and the patches can change its position frequently and as mostly it is painless it can go unnoticed many a times.. Dry mouth can at times occur due to geographic tongue where as there can be a number of other reasons like side effect of medicine,salivary gland dysfuction, nerve fdamage, infections like thrush,dehydration,Sjogrens syndrome etc.. While fissured tongue has been seen at times with ageing and can have a hereditary origin while the exact cause is unknown.. You should consult an Oral Physician and get evaluated so that he can do necessary investigations and make a final diagnosis.. For geographic tongue if there is no discomfort not treatment is required while for pain and sensitivity voiding hot and spicy food and application of numbing gel over the red area and steroid oral paste can relieve.. For dry mouth treatment of the underlying cause can resolve the problem.. As of now taking saliva substitutes known as Artificial saliva and chewing sugarfree chewing gums to stimulate saliva flow can help.. Keeping the tongue clean by using a soft tooth brush to clean the fissures can help in prventing infection.. Hope this information helps.. If you find the answer helpful please give me a Five Star Review and click on found the answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora..