Hi Dear, Welcome to HCM. Understanding your concern. As per your query you have symptoms of red blotches running from the armpit to shoulders which are due to allergic reaction or body s response to external stimuli which can be a allergen. There are number of factors that can cause this like seafood, tree nuts, and shellfish, medicines, milk, eggs, peanuts, insect bites and stings. Need not to worry. You should maintain complete hygiene and avoid exposure to sunlight. You should take plenty of fluids. I would suggest you to try to figure out what exactly causing red blotches in your case , give cold compresses to affected area to get rid of itching , take benadryl and consult dermatologist for proper diagnosis doctor will take history and prescribe steroid medicines . Hope your concern has been resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari