Hi. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain dry mouth is one of the most common cause of altered taste known as Dysgeusia and it occurs due to deficiency of saliva as saliva is responsible for maintenance and protection of taste receptors which are taste buds and are present in the papillae.. Saliva also helps in production of taste by interacting with different ions like bicarbonates and glutamate.. In absence of saliva the entire process is disturbed.. The redness of tongue is due to inflammation and is known as Glossitis and is also due to dry mouth.. You should consult an Oral Physician and get evaluated to get ruled out for the cause of dry mouth and treatment can be planned accordingly to improve the symptoms.. As of now you can take SALIVA SUBSTITUTES containing methylcellulose which can be instilled in mouth to provide lubrication.. SALIVA STIMULANTS like lemon drops, sour candies and sugar free chewing gums can help in stimulating saliva flow.. The oral physician can also advise you drug PILOCARPINE as it has secretary action and can stimulate saliva flow.. Drink plenty of cold water to relieve the inflammation and maintain hydration.. 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..