Bless you, Dar. Trapper's probably right. When my mother-in-law had the same thing happen, her dementia was advanced and she would drink only the barest amount of liquid. She would always sit with her feet down; we could not get her to keep them elevated, or even to move about much to help with circulation. No shoes for her either. She was in nursing care at the time, and eventually her foot became infected. They insisted on hospitalizing her, and after a day of being hooked up to i.v. fluids, she revived in a most astonishing way. Her dementia didn't disappear, but she had increased energy, focus, and vitality, enough to enjoy leafing through a magazine, which she hadn't done in a very long time. Sad to say, when my husband halted her further treatment after 10 days so she could be discharged in peace, she deflated after they pulled out the i.v. line. By the time she was delivered back to nursing care, her brain had retreated even deeper than before.
All to say, yes to fluids, if at all possible. I'm terribly impressed you've been able to keep her medication-free :)