Struggling with my reaction....

My elderly parent chooses to take care of health in a haphazard way. I struggle as it seems she doesn't tell any other of my siblings she has an issue until it is troublesome. When told by them to see a doctor for example will go. Where when I mention the doctor she almost yells at me.
When I was very young I was exposed to a different treatment than the other siblings. It effected my mental health and in the present get a physical pressure when talked to about health issues and refusal to go to a doctor.
A while ago chest pain was being experienced for a while and when advised I took parent to ER. After investigative procedure which went wrong there were three near death experiences. I informed nurses each time something was wrong. When I finally went back home after caring for my parent, waited till they could drive again, I experienced another PTSD response . Took a year before I could process the experience.
This experience repeats on me with the current behaviour by parent.
Anyone got any advise about taking good care of myself while trying to care about an elderly parent is getting older while resisting. This parent lives alone and is fiercely independent. Help!?!?