Both my two had terrible diaper rashes as well. They've got my English skin and they're sensitive! I am always on the prowl for a cream that has the highest percentage of zinc oxide in it. I prefer all-natural and homeopathic remedies, but honestly, plain old Desitin, at 40% zinc oxide works best for us. I slather it on by the handful!
When the rashes get really bad (bleeding, raw skin), I just pick up all of the rugs and let them run naked. Fortunately we have wood floors! It's a pain to clean up after, but that skin-air contact seems to be a miracle, and it's even better if you can expose the rash a little to the sun (obviously you don't want a sunburn, so keep it short!).
When mine were as young as your daughter, I could sometimes do the naked time in a pack-n-play, which helps with the clean-up, and there will be cleaning up; they seem to just wait for a chance to pee without a diaper on!
Hope it clears up. It's so hard to see your little one hurting.