Sjogren's Syndrome Support Group
Sjogren's syndrome is an autoimmune disorder in which immune cells attack and destroy the exocrine glands that produce tears and saliva. It also associated with rheumatic disorders such as rheumatoid arthritis, and it is rheumatoid factor positive in 90 percent of cases.

Hopefully others will have more suggestion, but you definitely need to see a rheumatologist.
My eye exam was done by a dry eye specialist. He did a lissamine green split lamp exam to check for corneal erosions and damage to the lining of my eye sockets. That same day he placed plugs in my lower eye lid draining tubes that helped hold eye drops in my eye longer.
With a good dental prevention program, teeth can be maintained successful in spite of the dryness. I use Evoxac, a power toothbrush and Water Flosser (AKA: Water Pik) to stay out of trouble along with MI Paste, a mineral paste (look for other posts on the subject) and fluoride.
Good luck!!