Hi, Willow, as Krista said in the last post, Biotine helps, but it is temporary. I have to use biotene toothpaste because anything else makes my tongue sore and bleeding--yes, sometimes I taste blood. I also use the rinse. Rinsing with water and baking soda provides temporary relief, but it's best not to use hydrogen peroxide except occasionally because it stains the teeth. Drinking lots of water every day helps to hydrate and also rinse bacteria away. But honestly, I haven't yet found anything that puts the sjorgrens out of commission and stops the flare; it comes and goes as it pleases. Very painful, though.
You mention you've just taken antibiotics. Did the white coating start during or right after this prescription? If so, it may be thrush, an overgrowth of yeast, a common side effect of some antibiotics. Yogurt and probiotics are often used to cure yeast, but I use a prescription mouth rinse from my dentist when I develop yeast.
Like you, I have TMD (tempro-mandibular disorder) and my teeth are chipping from the dry mouth. It's important to keep your teeth clean when you have dry mouth as the lack of saliva can lead to decay, but if you're like me, some nights the pain is so bad that you just don't care! I, too, experience the nasty taste and food often tastes 'weird' or 'off.'
I was a periodontal hygienist BF (before fibro), so I'd suggest that you see your dentist, who may or may not help. My dentist recommends biotene, prescribes the medication for oral thrush, but ignores my chipped teeth. However, if you have chipped teeth that are rubbing or cutting/scraping the tongue you need an appointment to have them smoothed off so that they don't make things worse.
Good Luck, and God Bless you!