My 101 Year Old Mother, Suddenly Became Extremely Confused, Unaware

My 101 year old mother, suddenly became extremely confused, unaware of what decade it is, was swinging her legs from the knee down while sitting on the side of her bed, like a child, and her blood pressure was 125/101 (on medication). It came on suddenly and worsened quickly. There's no UTI and an MRI shows nothing; I was told she's not dehydrated. She's not sleeping well, the past night or two, and is understandably upset about being in the hospital. Her feet and hands are always cold and bluish, which people say is due to old age - well, to me, that just means things aren't working like they should, not that they're okay! Could this be another problem with the carotid arteries, which she had before, or with peripheral vascular disease, or can you tell me what other issues could cause these symptoms? I realize more that one thing could be going on here.