your question needs more elaboration at this point as several conditions need to be ruled out before making a confirmed diagnosis.Also some nice and clean pictures of the involved areas would be of great help to recognise the condition.Many things can cause such type of rash
with such a short history,
allergic contact dermatitis
so i would suggest to see your GP or Dermatologist
or contact a dermatologist here on the site for a live chat.
thanks very much and all the best.