Hi Gaz! Something you may not have been tested for is copper poisoning.  The tests for this are hair analysis and/or a 24-hour urine catch.  Your doctor should be able to do either or both of these tests.  The body will dump copper in different ways.  Sometimes through the skin.  Your source of copper could be your house ...

Hi I have seborrhoeic dermatitis in the form of dandruff, but it also creates scaly patches on my forehead and beside my nose. I find that dabbing it with a cotton swab dipped in rubbing alcohol makes it go away. I mix the alcohol half and half with water sometimes and sometimes use it right out of the bottle. And it stays away for about a week. ...