What Causes Skin Abrasion On My Legs And Hands?

hi, for about a year now i have been experiencing skin irritation mostly on my legs and arms. first it feels as if i have a normal itch but when i scatch the area swells up as if i scatched too hard. the weird thing about it is that it goes away in about an hour and a half as if it wasn't there in the first place. Also the irritation sometime forms small bumps like a rash but there isn't any flaking or blisterlike head on the bumps. Also, it too disappears in an hour and a half. This occurs more daily and the last few weeks. The areas that it occurs varies but mostly on my tights in my arms.