Skin rashes are diagnosed clinically based on the history and appearance of the rash. However, it seems that you might be having some type of dermatitis such as allergic contact dermatitis or irritant dermatitis due to the repeated injury to the skin in your naval/waist region. It may also be folliculitis due to trauma/ infection of the hair follicles. Folliculitis is usually a superficial infection caused by staph bacteria.
You should try to wear loose clothing and apply some local over the counter antibiotic cream for a few days. If however, you find no relief in symptoms or the infection spreads, you should consult a doctor.
Do write in if you need some more information.
I forgot to mention both of my ears inner skin; not completly in ears and outer behind my ears have the same itchy crusty rash. Is this also dermatitis?
I have a rash on my stomach, it started on my arms just below on wrist. now has logalized on my stomach it gets better for a afternoon and then is back it itches really bad. i have put all kinds of cream with no help. i have gone to a dr who gave me steoids which helped only as long as i was on it. then it came back. this has been going on for three months please help.