Hi, Liverbird. I think Dexamethasone is probably a corticosteroid, given to reduce inflammation and pain, and that you could check it out further either generically (injected steroids) or by its proper name.
I had steroid shots over the years, mostly for widespread itchy skin issues. They made me slightly agitated & hurt locally for hours (couldn't sit comfortably

). Otherwise, the injections quelled my itchiness quickly and caused me no harm; but since everyone responds differently, we always should monitor our individual reactions, esp. to meds that are new to us.
Is "AS" Ankylosing Spondylitis?
Re: Sjogren's, was the anti-Ro autoantibody found in your labwork? Did you have a lip biopsy? (I think lip biopsy is the most definitive test for Sjogren's.) You don't have to answer, of course... I'm only curious because I have a form of lupus that features anti-Ro, and some of my symptoms were Sjogren's-like. BTW, there's a board for Sjogren's that you could check out, if you wish.
I hope this helps a little bit, that you post again soon, and that you can get more info straight from your doctor when you see him on 3/7. Let us know how you're faring, when you have time, OK? Bye for now, best wishes, Vee