@ggb21 your rash and location of it certainly sound challenging. I wonder if you might try something like lambs wool/sheepskins padding to wear on your skin and between your bra to keep pressure off of your sores and provide relief by way of the natural lanolin? I've used it for years when I was a figure skater to protect open ankle sores/blisters from breaking in new figure skates. Here is a link to some additional information if you are interested: https://engelworldwide.com/natures-band-aid-sheepskins-amazing-medical-uses/

Have you ever heard of this before?