Does anyone have any idea of what could be causing this? Any help is greatly appreciated. This is an outdoor cat only and besides this rash on her back toward her tail, she seems to be acting fine.
This could be an allergic reaction from a bug bite (possible a flea?) or really just about anything. Can you get her to a Vet to have them check it out? If not, could you send this picture and have them look at it?
Does she scratch at it, etc? If so, she might get some relief from cooled down Chamomile Tea, but until you figure out what's causing it, I don't think that will be the cure, just some relief. Here's a thread about using the tea:
That really looks more like a severe reaction to a flea infestation, as mrsgreenjeens
said, than anything else. I can't think of any better advice than that she has already given you!
it looks like allergic reaction to flea bites, it looks like this photo almost, like the bites look spotty, but due to irritation all areas around his skin is inflamed.
You may look to get diatomaceous earth and sprinkle it over the cat incase there's flea eggs. It does no harm to the kitty (other than dry out the skin) and if there's any flea eggs it'll help kill them off.