what's with this rash that comes and goes?

i have been getting this rash since i was little. it looks like hives and it spreads fast. it usually only lasts a day, but it is itchy and sometimes causes pain and swelling. i was told 7 years ago by a doctor that i am allergic to my own skin and the rash is caused by my scratching when i have an itch. i don't know if this is it though. the past 2 months i've been getting it almost everyday. what else could it be? more specifics: the rash used to mostly show up on my face. under my hair, forehead, around my eyes, and chin area usually. it still appears in those places, but it also appears all over my body. especially my chest, arms, hands,stomach, and under my stomach.what's going on?