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.

I frequently take Mucinex; I have for years.
I also have a semi-frequent whistling in my chest when I breathe and I can't eat anything cold or frozen because it makes it hard for me to breathe. Rheumy says it is SS lung and bronchi involvement.
I sure hope you feel better and flare free soon.