I may be out in left field here but it's something I noticed with my own. I couldn't figure out why two of my girls would scratch and cause matts in the same places, usually worse a few days after their baths. I changed shampoo and no difference. Then I watched a grooming video that warned against putting shampoo on the skin. I started diluting the shampoo in a squirt bottle and putting it only on the hair. Of course some gets on the skin, but very little. This one simple thing has made the unexplained itching decrease by 75%. I'm guessing it's because the shampoo doesn't remove the essential oil from the skin and the skin stays healthier. I bath once per week and brush every day. It's just something you can try that doesn't cost anything. Good luck!
