Westies are well known for having several skin problems.. You didn’t say wheter it is warts/cycts, or itching..or bare spots or sore and red…
Perhaps this site will help you identify the problem.
If your dog is itching, scratchiing, and chewing her skin, this is a symptom of canine Atopy.. This is a good site to help you understand and deal with this condition..http://www.petalia.com.au/Templates/Stor…
At this season, it is likely to be pollen related or mold/mildew..But household cleaners often aggravate the condition..chemicals such as Swiffer Wet jet, Carpet cleaners, air fresheners, etc..
It may be of help to feed a food that doesn’t contain corn or wheat.