Could it be an contact allergy? Perhaps she is allergic to a certain grass, weed etc in your area? Have you tried giving her Bendryl?
I use Isles Paste when our Weim gets a rash on her tummy. It is usually found in the baby isle. I actully found out about it when my daughter was young and would really bad diaper rashes. The only thing is it is really thick and pastey--so I would watch your furniture..

I still use it when my daughter gets a rash on her legs or arms--she has very sensitive skin
Welcome to BPO. OH, did I mention I
LOVE bloodhounds!!! I just posted a post last week wanting to know pros and cons...lol
Good Luck I hope your girl finds some relief.