Hi, Sexyhoney (and mga sis.)
Suffered this too for more than a year then bumalik saglit. Partly due to hereditary. My mom has it too. I opine its also due to chemicals and irritation. Sa akin nagsimula when a part of the back of my right leg keeps rubbing on our plastic chair. Hindi ko pinansin at the beginning until it spread
To make a long story short ay I tried various meds. Malaki rin na nagastos and parang walang solution in sight

Mahirap pa hirap ka makatulog dahil sa kati

So I searched the web and found that olive oil can help. Yup. Olive oil lang.
Well, not just lang. What I did was syempre slowly iwas sa mga pwede mag-trigger one of which is milk

Then mixed unscented baby oil sa olive oil 50-50 mix muna. Medyo masakit rin sa bulsa kasi ang cost ng olive oil - I got to use both virgin and extra virgin as depende what's available sa store malapit sa amin. Kapag hindi matiis yun kati then and only then ko gamitan ng gamot. Lousy sa Watson's as they don't restock with the same brand. Iyong cheap China-made medicine mahapdi nga pala so didn't bother using it na.
FYI. Masakit sa bulsa yun olive oil kasi I use it whenever the itchiness begins na naman. At least no side effect kung napasobra ka in using it as far as I can tell.
Gumaling naman but it returned when the maong I wore (bago) irritated the skin muli - same area

So ginamot muli and tinabi muna yun pesky pants. Its not a branded one na maong nga pala. I opine its the dye they used as well as most likely yun material as the other maong I bought okay naman.
Used cotton to dab on the affected part when using itong olive oil mix or olive oil na puro.
When it weeps noon no choice but to use yun steroid something meds. As much as possible do not scratch and pwede mag-affect rin sa hands and neck. Had to find something like the olive oil kasi kapag sobrang tapang ng meds my neck gets irritated rin. Well, wasn't sure dahil mainit that time so it may just be me scratching and hindi ko napansin na kahit maiksi nails ko it still placed the pesky germs or what.
Can't say for certain if this would help you but for those na naiinis na sa using meds (and butas na ang bulsa due to that) ay its an option to consider.
A thousand thanks to those who posted and shared here. Oh, did try those sulfur soaps too. Yun isa rin na ointment na sinabi huwag na ninyo bilhin for use I agree. I forgot the name but nasa white and green tube. Hanapin ko nga uli para mai-share yun name. Yun soap na for skin na gawa ng pari sa Don Bosco Mandaluyong I ran out of that and haven't gone back - though hope he is still okay and that soap is still sold.
Sa sulfur soaps mas mahusay yun Kaufmann per experience but the others work rin naman. Just follow the instructions.