Thanks for the query. You both should see your doctor who can confirm if it is Chicken pox
or other skin rash
problem. Does any of you get sharp pain
To answer your question, Chicken pox can happen in anyone with compromised immunity. Also, there might be simultaneous bacterial infection too.
Treatment is generally symptomatic but if your doctor confirms it as Chicken pox, he might do some test to find the cause AND he can advice vaccine
Hope you get better soon!