I dont know why you are advised not to bath but I would suggest the opposite. A bath in oatmeal or black tea bags will help with the itch and a bath can be medicated to help heal. 
 As long as your first wash is in a shower to ensure any oil residue is off then a bath is a great idea. Itll also help a bit with the mental aspect of the rash.
 I have had it there as well and found that hot water helped with the intense itch. ( that seems to be worse there than anywhere) I used it as hot as I could tolerate and it felt like a good  scratching but without the skin damage. 
 Ive used lots of crazy things on the rash over the years  but never in my shorts. 
 I would suggest talking to your doctor because they will be sympathetic and help you out.
 Dont worry about embarassment, theyve seen it all before.
 good luck. |