What Causes Swollen Itchy Spots On The Hands And Feet?

Hi, may I answer your health queries right now ? Please type your query here...I keep getting these red itchy swoolen spots on my hands and feet. They only appear on at a time and the middle of the swollen spot is either blue or white. The places they appear get so swollen it feels as if my skinis going to pop. They go away then appear ina dfferent spot. Not using anything new