I think, for me, there eventually became a difference between the pain and soreness, which was about the surface of my skin, as opposed the nerves jangling. I did get to the point where I could wear a bra, but that might be because my bra fitted closely to my skin, so didn't move about and irritate it. You might find it a bit different, given where your rash is, because your clothing is irritating your skin by moving about and triggering your nerve cells. Maybe you could think about something like Spandex to keep a constant pressure on your skin, rather than the intermittent triggering of your usual underwear?
My jangling did abate something like 3 or 4 weeks after the onset. It has re-occurred on occasions, though very briefly, for a few months thereafter.
I think that as you've still got nerve pain, you should go back to your GP and ask for specific pain meds as others here have suggested. There's the view that shingles occurs because of a reduced immune system - lots of possible reasons for a temporary blip in the immune system, and stress is one of those.
Physical pain can cause all manner of problems, including stress, especially if you can't get enough of the right kind of sleep. So it can end up as a circular kind of problem. Good GPs have a better handle on that than some specialists, so if you have a good GP maybe ask them for some heavy-duty but short-term pain meds, just to get you back on track.
Until I had shingles, I'd never experienced an illness that could make me feel so low for so long.