Reaction to Delva Conditioner?

I have had a rash all over my chest, back and scalp for about 2 weeks now and have visited a doctor and a dermatologist to get it cured (and maybe find out the cause so I can prevent it happening again). The rash is red and itchy...basically it's "hives" and I have been trying to think of things I have changed over the past couple of weeks that may have caused it. After eliminating washing powder, food, clothing, drugs (I don't take em!) and pets.....it occurred to me that I had changed from my usual conditioner (PPS) to using Delva pH conditioner about 2 weeks ago. I have stopped using this now and am seeing if it makes any difference. What I wanted to know, is has anyone else had any reaction to this product or knows of anyone who has? I am usually a fairly "unreactive" person, so it doesn't seem likely I would react to a conditioner....