Hi..
Thanks for the query...
I have gone through your query and can understand your concern..
As per your complain, the symptoms that you are facing of
dry mouth, salty lips, encrusted lips and excessive thirst when you already have autoimmune diseases can be due to Sjogren's Syndrome..
In this condition there is reduced saliva flow and even other secretions of eyes and body leading to dry mouth..
Excessively salty sweat can be due to reduced watery content..
I would suggest you to consult an Immunologist and get evaluated and proper evaluation along with investigations can help in diagnosis and treatment can be done accordingly..
As of now you can gargle with specialised mouthwash like
Biotene to reduced dryness..
You can chew sugarfree chewing gums and suck tart candies..
You can also instil artificial saliva drops containing Methylcelluloe..
You can apply Petroleum jelly over the lips and around to keep them soft and prevent encrusting..
Hope this helps..
Regards..