What Causes Itchy Rashes On Waist Line?

I am 31, 5'7" 160 and no real medical history. I have been experiencing an itchy rash on my waistline for almost a month. It does not itch all the time but when it does it is horrible. The area has become a little raw and dry from scratching it. I tried hydrocortisone and it only temporarily relieves it. Just wondering what it might be, how I might fix it or if I need to seek medical care. Thank you.