Can't figure out how to talk to Grandmas GP?

Hi,
My Mum/Grandma (she raised me) is 72 this year, We're in Melbourne, Victoria, Australia.
I've talked to many people about my concerns for her and a lot say that she could be in the early stages of alzheimers etc.

She doesn't eat properly and is reusing her cutlery and dishes had been going on for months now etc.

Today I ask her where her doctors clinic is, she says beach street.
I've called the only two medical clinics on beach street, one which she has attended only 6times to 6 different doctors (starting late last year 2014) and only has attented the clinic once this year, when I know for a fact she's told me she's going to the doctor a few times this year and everytime I've asked what clinic she says "On Beach Street". The other has no record of her existing.

I then questioned her subtly on her doctors etc. She says she has a main doctor she sees and she's been going there since Brad (her 1st son) or even before him. So apparently according to her 50+ Years. She also says that they are moving this Friday and relocating somewhere near the cemetery.

I've asked these two clinics if they're moving and they had no idea what I was on about

Yet she hasn't always lived in the same state. No doctors clinic I can find has existed for that long but maybe she's had the same GP and he's changed clinics. I'm not sure.

And also today I Told her at 10:30am I have a YWC Appointment she thought it was the Old RACV building AGAIN, I AGAIN told her it's not the old RACV building which she doesn't remember has been changed to Headspace even though I've told her a million times. Told her also at 10:30am I had the Appointment at 11:15am. She told me it was no problem to do this.
At 11:05am I came downstairs to go to the appointment with her. She was convinced it wasn't even 11am yet and didn't believe it was so until she checked the computer time. She then continued to eat her toast and have her tea slowly, using the computer casually (even browsing still). I told her again we had to go and she said she still had to have her tablets and proceeded to do so by this time it was 11:10am. Then she looked for her keys in several rooms when they were right next to the computer. We then left a few mins later.
She then started to turn towards Headspace. I told her it's not this way she then exclaimed "oh sorry I thought we were going to the old RACV building" Then asked me where we were going. I had to direct her AGAIN to the YWC.
As she AGAIN couldn't remember where it was. 
She only took me about 2weeks ago and about 2weeks before that appointment too and on other occasions as well.
She also keeps commenting on my clothing never remembering to have ever seen the clothes before.

Also later in the day I went to take my dog for a walk and she must of overheard me talking to the dog but she asked me abruptly "What's happening?!" And I asked what did she mean and she asked me who was there and stuff and I said no one and she was convinced she heard another voice talking to me?

But yeah,

I'm finding it difficult to find her Doctors Clinic and GP.
There's also a lot of Privacy/Confidential Issues etc.
What can I do to let them know I am concerned?

I have tried confronting her before about things but she either gets very defensive or comes up with excuses.
I'm 20 this year her sons are a lot older than me yet don't see her as often as I do, a lot of the things she does are very subtle and you could only really tell over time that things aren't quite right.

Her monthly credit card bill this month is $6,000-$7,000 & I don't see how she could of managed to do that either.