What Causes Itchy Pinkish Rash On The Forearms And Legs?

Hi, last week i noticed a pinkish rash on my forearms and legs, it itches sometimes but not frequently. Now it turned into a goosebump looking rash. I am 30 years old and this is the first time I've had this. At the beginning I thought it was a food allergy but its already been a week and it seemed to disappear into these goosebumps. Please let me know what this could be. Thank you