YLL, I get that!! Have done, off and on, seems like forever! I never heard of anyone else with it before now!
Okay, the diagnosis I have had is for fungal infection, apparently it is caused by being moist, not drying well, (though I have my doubts, I always dry well and it seems to just flare up with me, especially if I wear jeans, pants or anything that presses into my navel...). Anyway, I was, and still am when required, prescribed a fungal cream called Canesten, (the active ingredient being clotrimazole) and it clears it up in no time, especially if applied as soon as the problem is begins. I always try and make sure I have a tube, just in case!

Chris