What's the word for the caretaker at the end of life?

 When a person is put in the position of taking a young human, be it by birth; adoption; or life circumstances, to raise to self sustainability it's called parenting. What is it called when a person is put in the position of taking an old human to care for until they come to the end of their days? I can't find one word that sums that up to say what this process is the way "I am a parent" does for the opposite process. There ought to be a word for that.
   
 I have found myself in a position that I didn't think I would ever be in, caring for an elderly parent. My parents have both passed away.
     When my mother was ill, I lived several states away and was raising children. When I would talk about going to her and helping to take care of her, she and family members would say they had it under control and would let me know if they needed me. Mom would tell me to take care of my family.
     When my dad was ill, I was on the other side of the country. My family would say that they would let me know when they needed me to come. To wait until I was really needed. Then he was gone.
     I have described myself as "the bad child" for not taking care of my parents. I don't, honestly, believe that my parents would say that about me. It does show the guilt I feel for not being there for them when they needed care.
     My three, wonderful, sisters did a magnificent job of caring for our parents. The sacrifices they made will never be lost to me.
    
    Then, a couple of weeks ago, the tables turned. My partner's mother had a heart attack. Suddenly we were in the chaos of ER's; cardiologists; hospitalists; stents; pharmacies; and cardio rehab.
     We are thankful that she recognized the symptoms and called for help quickly. We are also thankful that we had just moved into our new home together and we have a place for her to stay until she stabilized.
     I never thought I would be pacing the ER floor over a parent. It is a strange place for me. While it certainly isn't what it would have been for my own parents; it has given me a stronger appreciation for my sisters support system. Husband, boyfriend, friends that rallied behind them and propped them up when they couldn't stand any more.
    As many people as we have helping us move into this next phase is phenomenal. We are learning the language of this new world and figuring out what works for our circumstances. There is an understanding of what this turn means. There have been discussions of last wishes and what to do when she's gone. It's a phase of life that I thought I was done with, I'm glad to be here in a support position. Still, there ought to be one word.

Then this:


I turned my head
For just a moment
A blink of the eye, really
An instant

I don't know how it happened
Seems that it was quick
Life being full of
Work, bills, days, holidays

I am not entirely sure,
Just that it took me by surprise
To turn around to find
You had gotten old

Not in numbers of years
That I understood,
In the person before me
That is you

Marking the occasions
Of first times once again.
Fear in your eyes, where
determination once lived

I knew it would happen
Someday had shown up
Caught us both unready
My heart begins to ache

You have turned down
The last road of life
I can only help you
Stay safe as you travel

Taking the car keys
Holding the bicycle seat
Grasping your hand
Supporting your head

The backward steps of dependence,
Of the end resembling the beginning,
Pretending you aren't dependent
Until we can't pretend any more

To say the child
Becomes the parent
Is not entirely true,
Parents get to keep their work