What Causes Severe Cough In A Person With Sjogren's Syndrome?

Hi, i have fibromyalga and sjogrens syndrome. I have very dry eyes, for which i use prescribed eyedrops had gel. Also i have a very dry mouth. My dentist, who observed that my mouth was drier than the usual dry mouth. I use a fluorine toothpaste, Duraphat , prescribed to help save my teeth and gums .Since Christmas i have had 4 bouts of a really barking cough. I have been told that i sound as if i had croup, it is such a bark !! It isnt a chesty cough. My GP said my chest was clear when i went for a checkup , on the 3rd bout. She diagnosed the so called 2015 virus which affects the upper respiratory system, takes weeks to go, and often returns. It doesnt make me feel ill, although i do feel a bit under the weather, perhaps a bit more fatigued than usual. I have just started the 4th episode, and i noticed tbat the day before, i had a very dry mouth. Dryer than usual. I have tried artificial saliva sprays, but find they affect my voice, particularly my singing voice.i rely on no sugar sweets, and mainly constant sips of water. I always have a pint, to hand! This usually helps me cope with the dry mouth. Could this latest bout of barking cough be due to the dryness? Are there any suggestions? Is there a definite correlation between this cough and Sjogrens?? Thanks Chrissie Smith