P.S. If you have a fever, see a doctor a this could be Scarletina, a strep infection.
Did you recently change detergents? Or perhaps your detergent is new and improved. It sounds like dermatitis - an allergic reaction to something you are using or wearing.
Could even be a food allergy. Have you added something new to your diet? Or is there a new and improved food on your list?
If you have pain with the rash, it could be Shingles. In that case, see your doctor for an anti-virus med.
Wishing you the best.