I understand your frustration - it's very difficult to watch our companions be ill and not have any idea why.
A hands on evaluation is absolutely necessary to know for sure - and that's probably why the vets won't discuss it over the phone, but I'll try to help you with some possibilities to be prepared for.
There could be any number of reasons for dogs licking floors/carpet, concrete, walls and even bedspreads or cushions. When a dog is stressed or bored, obsessive-compulsive behaviors may develop. Distractions, providing interest and outlets, attention directed elsewhere on a consistent basis may resolve the problem, but it takes dedication and perhaps even a slight lifestyle change on the part of the humans.
Hypoadrenocorticism (Cushing's Disease), liver failure or neurological disease may also be at least part of the cause.
It may be a tooth or gum problem too. Even if you can't see anything, it could be something going on under the gums or in the root of a tooth.
Since she's also acting 'off' in other ways, I'd be more concerned and not hesitate to have her seen first thing tomorrow. Even if you have to find an urgent care clinic (which is quite often a regular vet who keeps 24/7 hours).
Keep up the good work and excellent observations. I hope she's fine.
I can appreciate that. It's always easier to handle something you're prepared for right? This could also be nothing more than OCD (yes, dogs can have obsessive compulsive disorder) - but to be honest, that would be harder to take care of in many cases.
Let me know how you do ok? You can re open this question any time and you do not have to press accept again.