Hello Dear Thanks for your query, I will be most happy if I could help you out. First of all be relaxed and make your wife relax and reassure her. I have thoroughly gone through your query and found that you have not mentioned few things, so it is difficult to reach on any diagnosis on the basis of these two signs(dry mouth+skin rashes). If someone with same symptoms arrives in my clinic, I must ask few questions - Since how long time the problem is occuring?? - Are you having any problem like dryness, redness or burning sensation in eyes?? - Do you also feel pain in joints ?? Now if we combine all these signs and symptoms i.e. dry mouth+skin rash+dry eyes+joint pain, it may take us to a condition known as Sjogren s Syndrome, which is an autoimmune disease and only symptomatic treatment can be provided. The problem may be due to any other reason also. So here our first attempt is to reach on a correct diagnosis which is very necessary to plan and initiate the treatment. So I advice you to must consult an oral medicine specialist as soon as possible so that the exact diagnosis can be made through thorough clinical examination and investigations. Hope this will help you If there is any more query or question regarding this in your mind, you are welcome to ask me any time. Take Care Regards