"How can I help someone "believe" or "understand" when I see that person is unable to hear the answer?
The first step is to think about her when you are not with her. Your belief in her well-being, no matter what her own perception of herself, is the uplifting fulcrum you provide. There need not be any words, because she can't hear them, but simply your unwavering understanding of what she really wants (and is hers, since you know she has asked and has therefore already created...)
The second step, when you're with her and hearing her pain is to accept and appreciate that she is where she is, and you need not FEEL the problem with her in order to make her feel understood. It's an important part of her experience. She wouldn't appreciate the improvement if she had not felt the lack of it.
When you observed her discomfort, you naturally got spat out of the vortex.
Return to the vortex. If you need to excuse yourself from the room for a moment in order to do so, then you should do so. In the vortex you KNOW she's fine. When someone is in the presence of someone who knows of their well-being, the recipient of that knowing benefits by it.
Here's the important point: The other person's well-being is assured, whether she knows it or not.
She'll be led toward her own best interest, whether she's aware of it or not. Everyone is here for the experience of physical life and for the joy of figuring it out on their own.
When people ask questions of you, they're almost ready for the answer. If they don't hear it right now, that's okay. There's no danger to them and you haven't failed.