What and how should I document my dad's mental and physical health issues to doctor?

From a previous post, it's not clear if you have POA. I agree, your letters maybe in his file. But not being a POA or on his HIPPA paperwork the doctor is not allowed to talk to you.

What I did was keep notes of Mom's changes. Just before her appt I would compile them in a Document. Easy to read font and 1, 2, 3. Only one page. Don't go into a lot of detail but enough. I then hand it to the receptionist asking that he review it before he saw Mom. This helps the doctor know what type of questions to ask. But in your situation, the GF maybe handling the cards.

Are you saying that the doctor doesn't know about your dad's physical condition?

That doesn't make any sense and if it is true, you should be helping him find a new doctor that gives a care.

Reisenburg, if you are able to make a doc appt for him using a "therapeutic fib" (something like, new Medicare rule requires annual physical). Accompany him to the appointment and have a pre-written note to discretely hand to the nurse prior to the walking in to exam room that requests dad is given a cognitive exam during the visit. Before you leave the appointment go to the receptionist's desk and ask for the Medical Representative form. If you can get your dad to simply put you as his designated representative (and then sign the form) THEN that doc can discuss anything with you about your dad. You need this form for every different doctor he sees. Sometimes I just tell them I'm my mom's medical advocate and they allow me in the room during the exam. I can get in with my medical PoA. But discussing info in the absence of the LO is another matter and requires that form.

Due to HIPPA laws it’s likely the doctor can’t communicate with you. You can let the doctor know whatever you need to but he/she can’t reply back unless your parent has signed a release