After reading your history it appears that you might have developed allergic dermatitis
to some contact allergen. You recollect anything new coming inyour contact before appearance of the rash. I advise you to not pinch or pop the area otherwise these areas are very prone for getting secondary infection. You can apply an steroid
cream such as cortisone
If itching is present then can take benadryl
accordingly. Apply a plenty of moisturizers over the affected area.