What Causes Itching And Burning Sensation Around Inner Thigh And Underneath Arms?

Hey. Iv been suffering for about a year or so with itching around my inner thighs and underneath of my arms. Iv read problems online about groin and armpit but mine arent those areas, and there isnt any rash or anything abnormal that i can see, it will just start itching randomly, and then feels like a burning sensation which continues for a while after. What could this be?