Hi.. Thanks for the query.. Dry mouth is the cause for soreness and itching.. Dry mouth can cause irritation of the mucosa along with mucosal thinning.. Altered taste is due to reduced saliva flow only as the saliva maintains taste buds and in the absence of appropriate quantities of saliva there is alteration in the function of taste buds leading to altered taste.. Common causes of Dry Mouth can be: -Severe dehydration -Side effects of medications if you take any. -Salivary gland dysfunction. -Nerve damage supplying salivary glands. -Oral infections like thrush.. -Sjogren s Syndrome..etc.. -For dry mouth chew sugarfree chewing gums.. -Drink plenty of water. -Avoid regular mouthwash and use specialized mouthwash that are formulated for dry mouth patients like Biotene.. -You can also instil artificial saliva drops.. -Suck tart candies as it also stimulates saliva flow.. If does not improve consult an Oral Physician and get evaluated.. Hope this helps.. Regards.