Hello Troy
@Troy63 and firstly welcome to this friendly and supportive forum. There is a lot of shared experience of dementia to be found here, so I am glad you have found us.
I am sorry to read of your father. You will know, I'm sure, that memory issues are common in people with dementia. Is he on any medication for his dementia prescribed by your GP.
If this is a sudden change to his behaviour, it may be worth getting him checked out for a possible UTI. When there are sudden changes it could be that your father has a urine infection. It is remarkable what changes an infection can cause. Normally treated with antibiotics.
Now that you have found us, do have a good look around the forums and ask any particular questions you may like to. Members here really do understand and want to help.