Excessive sleepiness and severe difficulty walking

My mom is 65 years old (she turns 66 in July) and has been living with a dementia diagnosis for about 3 years.

Her condition suddenly got much worse this past Sunday. She developed severe difficulty walking almost overnight. Before that she was able to walk with assistance, but now she is extremely weak and barely able to move.

On Monday she slept until around 7 p.m. After I woke her up to change her diaper, she did eat and drink, then went back to sleep. Today she’s sleeping almost the entire day again.

I’m wondering what this could indicate. Could this be a UTI, even if she doesn’t have a fever? I’m planning to get her urine tested as soon as possible.

She had blood work done about two weeks ago. Most of the results were okay, but her liver function tests were abnormal. At her recent appointment, the geriatrician decided to stop her allopurinol and her cholesterol medication because of those results.

Has anyone experienced such a sudden decline with excessive sleepiness and severe weakness in someone with dementia? Could this be caused by an infection, liver problems, medication changes, or is this something that can happen in advanced dementia?

Any advice or similar experiences would be greatly appreciated. Thank you.