I have itchy arms and everytime i scratch little bumps appear what could it be?

HK piliari: Often times scratching dry skin can produce irritation of the skin, especially the hair follicles which become small red bumps. If you are fair skinned, or have red hair, this is very likely. The condition is called hyperkeratosis piliari and can be treated by exfoliating the skin with a loofa, and then moisturizing with Eucerin or Cetaphil lotion to lubricate. It gets worse in the summer.