Catsnclay, I am sure your father is, above all things, afraid of what is happening to him, and in denial is his only way of coping. Others have given you good advice. Is there a trusted clergyperson you could get that would help you get him to a doctor? There are many things that they can do these days, and many causes for dementia - including if he's taking any medicines that he might no longer need ... and if it is something like Alzheimers, the sooner you get him help, the better for the both of you. Does he have insurance? Does he have any long-term care insurance?

And don't worry about being embarrassed by his behavior in public sometimes. Many people will understand exactly what's going on, and no one will blame him or you.