Long time ago, in another less happy life, the Ex had Shingles.
As the others have said, follow the Doctors advice.
We also found that
bioflavinoids for shingles can help.
(though I'd post a google search link to let you do your own reading)
Good Health Food shops will have them, lots of places have small amounts in with Vitamin C, try to get a strong dose with a mix of the various bioflavinoids, and not a lot of Vitamin C if any.
It's to help boost / support your immune system.
Also helps with Cold Sores.
Hope she gets some relief, and you both get your trip.
ATC