Dad's memory is deteriorating, and I'm freaking out

I (27F) am realizing that my dad's (70M) short-term memory problems are here to stay, and I'm freaking out. I knew his memory had suffered after a major surgery he had last year, but my family has spent so much time focused on his physical health that I think it's only really now sinking in, and I'm so freaking scared about what this means.

There's no official diagnosis from a doctor on his neurological condition, but my dad repeats questions/sentences in the same conversation, forgets to eat and take his medication sometimes, and has trouble finding words. I live in a different state, and my mom is still working a full-time job so he's at home by himself for a good chunk of the day. My brother also lives in a different state and has his own family to prioritize. There are so many things that need to get done, from moving my parents out of an old house to estate planning to an actual appointment with a neurologist... I'm overwhelmed.

What we don't know yet is scarier than what we do now, but I'm prone to anxiety anyways, so I'm spiraling pretty hard about if this turns out to be dementia or Alzheimer's. All my life, I've often had the thought that I could handle any kind of aging problem unless it had to do with his cognition, and now... It seems like it is.

I'm worried for my mom as his primary caretaker. I'm worried about my brother and his stress levels and how the two of us will communicate as we go through this shift. I'm worried about my dad and how to help him stay happy and healthy. I'm so, so scared of how bad this will get.