I have a non raised non ichy very small blochy red rash on my arm , any ideas what it may be?

Show it to your MD: There are many sorts of rashes. If it doesn't itch then its not an allergic rash. Most rashes are benign; some are not. Please show this rash to your primary care physician who will either recognize and treat it or refer you to a dermatologist.

Need to see to ID.: This rash would likely need to be examined and more history obtained to be able to provide you with useful input about the diagnosis or possible treatment.