I have known people to get chicken pox twice. It's not really a rash, but are spots that itch and then form a 'scab'.
What did her doctor say?
Chicken Pox are extremely contagious and have an incubation period before they show on the surface then are still contagious till the 'scabs' are all dry
You won't know you have them until you see the spots.
By the way, its Varicella Zoster, a form of Herpes.
Shingles, which my Mother has had for the last 4 years, along with her other illnesses, is extremely painful and is also a form of Herpes.
It's not all just the kind ya get from SEX