hi itchy rash on the face forehead can be due to irritant dermatitis
due to any coometics,or due to phytophotodermatitis
.i think there is no relation of shigles one year back along with this rash.
it can be treated with atarax 25 mg at bed time,antibiotic azithromycin
500mg for 3 days and application of calamine lotion.if not cured go for prednisolone
20mg and tapering to 5 mg within 0ne week