I do understand and sympathise. We had a similar time with my mum. What about arranging an appointment at the doctor for you, or maybe a phone consultation. Take, or have with you, a list of his symptoms and ask the doctor what he/she can do to help. They will have come across this situation many times, I'm sure. It does sound like vascular dementia, maybe early stages. Don't despair, there's a lot of support out there. Check out the Alzheimer's Society website - it got me through and I now volunteer with them.
I'd be careful with the filming thing though ... you know best, but how will he react to that?
Meanwhile, please do your best to look after yourself as far as you can, and do phone the doctor as a first step. As someone said, they may have a dementia nurse you can chat to, at least, and they will have come across this situation before.
Sending hugs.