I have recently developed a very deep bellybutton and am having similar problems. Is it normal for the bellybutton to turn into a giant hole? lol
I have a very deep belly button as well, which would usually have a bad odor and minor irritation. I tried multiple cures (powders, antifungal creams, tea tree oil, etc.) The absolute best thing I have used is Hibiclens. It is available over-the-counter and I had it on hand because I was using it in wound care for a friend. It claims to have "antiseptic activity and a persistent antimicrobial effect with rapid bactericidal activity against a wide range of microorganisms." I tried swabbing it in my belly button with cotton for about 30 seconds each morning and then rinsing it out when I showered. The odor and irritation in my belly button was gone within a few days. (Usually, to eliminate it I'd had to use an antifungal cream at least twice a day for weeks on end, and as soon as I stopped, the odor would return.) Now, I swab out my belly button every few days with Hibiclens, and it is odor and irritation free on a continuous basis. Hope this helps!