"Oh - I'm sorry." She doesn't sound like she disbelieves him, and she frowns.

"I... I don't know if I can help exactly the way you had in mind. But I'd like to try, if you're not opposed. I'd need to see the sick person, though."

She can't promise anything, but if she can look at the aura, she'll have a better idea of what she can and can't do.