Jennifer, I have chronic sinusitis along with Crohn's. I've taken Omnicef a few times in the last 4 years for sinus infections. It did give me D, but that went away after I finished the Omnicef. For me at least, it didn't really cause a "flare," just temporary increased D. But you might be different. Who knows?
A probiotic is a good idea - even just eating a yogurt or two everyday may be a good idea while you're on the antibiotic.
From your description of your sinus infection (especially your teeth hurting), it sounds like your maxillary sinus(es) are infected - they're the ones below your eyes and above your top teeth. When I'd get an infection there, my top teeth would hurt too.
Along with the antibiotic, and the yogurt/probiotic, consider the following things to help clear the sinus infection:
*Drinks lots of warm liquids (not cold liquids). Even warm water if you prefer.
*OTC decongestants, ie, sudafed. Decongestant nasal sprays are very helpful for short term use (2-3 days, not longer or you get dependent on them). Maybe just use the spray at night for the next 3-4 nights.
*Mucinex, which thins the mucus and helps it drain better (may cause mild upset stomach, but I never had a problem with that).
*Saline nasal spray - get this and use a ton of it, like 10 or 20 times a day give a couple of squirts into your nose. Don't worry about overdoing this - it's just salt water.
*Steam inhalations - heat up some water on the stovetop and hold your head over it, breathing it in through your nose.