My mother won't let me help her, what can I do?

Why won't mother let me help? I try to do everything I can - take her anywhere and do anything needed. She tells me she is sick and in pain but when I offer to take her to the dr or ER and she says no. I've begged and pleaded with her to let me help her and she still says no. All we do is fight! All I want to do is help and she won't let me - what can I do?