Acute & Prolonged Scalp Irritation and Hair Loss

About a year ago, after getting my hair highlighted (which I had done before), I noticed that my scalp was really itchy and irritated.  I used a medicated shampoo for a couple of weeks, but saw no improvement.  After about 6 weeks, I noticed significant hair loss, throughout my entire scalp, with concentrated hair loss on the top.  I've seen a dermatologist regularly, who ran some labs (all normal), put me on a course of steroids, gave me topical drops to massage into my scalp, and finally did a biopsy -- still no relief.  It appears to me that the onset was acute, and that the problem is with the scalp, with the hair loss appearing to be a symptom of the problem.  I can't help but think that there must be some type of shampoo that would be effective.  Any advice?

[Caryopteris]

You could be allergic to that hair dye.  Or perhaps you should be tested for Celiac disease.  Surely you were tested for thyroid disease?  

I'd recommend Wella Regulate shampoo as it controls oil and is very easy on hair and seems like an anti-inflammatory to my scalp and also fluffs hair.  Alternate that with Nizoral shampoo.  It helps regrow hair in a couple of different scenarios.  Expect slight extra shedding the first time you use it.  It's not much and is normal for any product that regrows hair.