My dad is 74 and had the symptoms of early dementia. But, still used a walker, fed himself, had conversations (although he might forget them) and could answer questions and even sometimes could cook a small meal. He also has diabetes, heart issues, and TIAs from a stroke 20 years ago. He had a major TIA 2 weeks ago and fell. He was alert the whole time and refused the hospital when EMTs came. He is a large man (300lbs). He went down rapidly after the hall and in 3 days he had another fall out of bed this time and we insisted on the ER this time. They did a CT to check for stroke (none) but found 2 broken vertebrae in his back. They held him for 4 days and then referred him out to skilled nursing rehab (in a nursing home). Since the day in the ER a week ago, he has declined rapidly. Cannot focus to answer questions or feed himself. Sometimes recognizes us but sometimes night. Sleeps a lot, like deep and unable to rouse. They did discover that he is a Co2 retainer in the hospital and he fights a cpap to blow that off so we aren't sure if we are dealing with dementia or a build up of Co2 in his system. We just didn't realize that dementia could progress so rapidly in just a week's time.
My mother in law had mild dementia, injured her back, went into the hospital and was given pain meds. She hallucinated and afterwards her dementia rapidly progressed.
Does he still have a quality of life? Does it look like he will walk again? It could also be delirium from the hospital stay. The spinal fractures and obesity will be hard to heal.
One thing you can ask about is Wegovy or similar med to bring his weight down. After all he is a diabetic. My friend's sister was 350 lb. She is now in LTC but is using the med to help her move around and take pressure off staff to get her up. Another option is to also ask about a hospice consult.
Then later my Mom had another serious fall that included a second head trauma. She was sent to a rehab center where she stayed for a couple of weeks, then she moved into the center's skilled nursing facility. Within weeks of her fall, her mild dementia was now in later stage. She could no longer walk, nor recognize us on a regular basis. She now needed a village to care for her.
I, too, was amazed at how quickly everything transpired. There were times where Mom's brain would loop to understanding some things. She thought she was in a motel in a town where her parents and siblings were living. I had to think of "therapeutic fibs" any time she asked to go visit her parents or siblings. Such as asking to see her parents, I would say "they are visiting the old country" and Mom would smile saying "that's nice".
And often it is a fall that will be the demise of a person as well.
Plus if he's hit his head in his falls, that could cause a brain bleed which isn't good either.
I'm sorry that you're going through this with your dad. Just enjoy whatever time you may have left with him.
I am afraid, with dementia, you have entered a no-man's-land of very few answers and a whole lot of questions, and it seems my pounding along on my keyboard every a.m. here amounts to a "who-knows?" more than anything else. Your best answer or your best guess will come from the neurologist seeing Dad at this time.
I wish you good luck.