Hi!
As an older person, I just want to tell you first of all that of course you are worried, and that's because you care about her. Good for you!
The best way to help her right now would be to keep encouraging her to see a doctor, AND, make yourself available to help her make the appointment and take her to the appointment, and be with her during the appointment if she feels comfortable with that. If she does have health issues, it's very important that she be seen.
The next thing I want to tell you is that you don't want to become the gung-ho daughter who is going to fix mom.

There is a fine line here between helping and pushing, and it's especially touchy between parents and adult children. If you think you can walk that fine line, and can be more her friend than her caretaker, then that's good.
She will need encouragement in all of this, and you can help--but don't put her in a position where she will think she's in danger of failing your expectations as well as everyone else's.
Good luck!
Jay