What Causes Itchy Rash On Arm And Elbow?

i have developed a colorless itchy rash on my right hand and a small patch of them near my elbow.....this past week the only difference in my diet is that i am on the daniels fast....which consist of 3 days of water and juice only and then fruits and veggies for the duration of the 21 days........should i be concerned about the rash? and what will relieve the itch ?