I suspect my grandma who lives alone might be showing symptoms of early onset Alzheimers, refuses to let me make a doctors appointment for her, what can I do?

F 25 5’2 135 pounds I tried getting her to sign a living will and poa she says okay and then goes back on it, it’s been a week of trying and her saying yes and then me visiting her and her saying she doesn’t want to anymore. Do I need a poa or can I just call her doctor and be like hey these things are going on can you call her and say she needs to come in for a check up? I just know if she knows it’s to check her she will not do it. I feel really lost and don’t know what to do, my dad passed away he was her only kid.