itching breakouts

This doesn't happen every day, i'd say about once a week (sometimes less frequent) my body starts to get a itching sensation, which is extremely hard to ignore.  It usually starts in one spot on my body then, eventually i'm itching in other places afterwards, then it subsides and i don't itch untill a while later (week or so).  usually when i itch myself my skin feels bumpy where i was just itching, almost like somesort of rash, except i don't think i have a rash...  Does anyone know what this may be, cause i definately do not think this is normal.