So sorry to hear and especially with the distance from her - both from you or your siblings. The only thing is ... if you did call her doctor and mentioned these things to the doc ... what can the doc do about them.
The stage of life you're describing can be a terrible thing for the adult child to deal with ... even when living close-by. Has anyone thought about getting or having a power of attorney for medical. That may not be the exact correct phrase ... but it allows someone the authority to make medical decisions for a person.
It is such a delicate thing. It can be extremely threatening to the older person ... but it may be necessary.
My Mother has been in an Assisted Living Home for Dementia for nearly a year now. And prior to that, she had a 24/7 care-giver living with her in her home for 15-months. Now, my Mother is 20-years older than yours ... so that would seem to make a huge difference. But it may not!
Whatever you or your siblings might do, I'm sure the safety of your Mother is likely the most important in making a decision. And, of course, finances become important too. I don't know how you force your Mother into going to see the doctor.
Is there a support group near you - for dementia or alzheimers? What I mean is a support group for the relatives or children of a person with dementia. That could be very helpful to you. I went to a local group here early last year several times ... and it gave me a better understanding of the disease, and of what I might expect, and of how to handle it.
Good luck to you at a difficult time.