On one hand your parents took care of you, therefore you are just returning the favor.  On the other hand, if you are the only caregiving child of many, shouldn't you be paid?
 
Many a family squabble involves this question with aging parents. Who gets what?  

So right here and now, I will elaborate one person's thoughts regarding this topic.

 First, I would love a world where the children got together with their parent and decided together what is the most reasonable and equitable way for things to be managed.  But so often these conversations are held multiple many times with all different family members. As a health care provider, I assure you we see it all.  Some families do an amazing job of figuring this out; others, not so much.
 
To start, collect your parent(s) and all of the children.  Video conferencing exists now, so there is no real excuse there, and do not use "there is not enough time" as one of them.  Talk through what needs to be accomplished.  Does the parent need round-the-clock care or just some help?  Whatever it is, dole it out fairly.  Make the arrangements an open book where everybody agrees.  Frankly, I would love to see it reduced to writing with everyone signing off.  (I bet that a lot of you are rolling you eyes on that thought.  I did, however, say this is how I would personally approach the subject. Being thorough and clear can only help you.)
 
In speaking of payment, it all depends on the situation and circumstances. Every family situation is different, and unfortunately there is no one best solution.

• If one sibling takes on the bulk of the care because of proximity, maybe mom pays a certain sum weekly. 

• If mom provided free childcare for that sibling for ten years, maybe it is payback time and nothing is compensated. 

• If mom has no money whatsoever maybe all of the siblings pitch in to pay a care giver. 

• Maybe one sibling lives with mom rent and food free in exchange for care, or mom hires a caregiver. 

 I do believe that accepting payment for the assistance you provide a parent should be an open book with siblings and fair. 

If you are working, and so much care is needed that you are no longer able to work, a reasonable solution needs to be found that involves money.

• What would a caregiver be paid?  

• Would a facility be more cost effective?  

• What does mom want?

These are questions to ask before decisions are made. As mentioned earlier there is no one solution.  Figure out what works best for your family, have everyone agree, reduce the plan to writing, and move forward. I do recommend seeking outside, unbiased professional advice if you are struggling.