Welcome to HCM and thanks for posting your query
It will be quite difficult to give an impression about your problem without actually seeing your lesions and given the fact that 3 doctors have already seen the lesions. Non the less, I will try to throw more light on your problem by giving my own impressions.
Per your description, one will immediately think of scabies
* location of itchy rashes from neck till feet (typical presentation of scabies). We rule out allergy because of limitations away from the head (allergies are usually diffused-completely in entire body or restricted to specific regions of the body -arms, legs, head etc depending on the cause of allergy).
If I could get more information about the color, consistency, demarcations -rings?, linear?, parallel? etc, distribution (already mentioned), areas of high concentration, level above the skin level (macula, papula, pustula, vesicula etc) etc.
It could be scabies that is not properly treated with proper medications as the two molecules you mentioned are no longer approved for usage because of their various defects. Benzyl benzoate
10% is recommended for a 24hrs application. Remember that it is very possible to be having scabies and your wife is not manifesting the condition. You might require antibiotics prescribe by a doctor or dermatologists if scabies is infected. Other medications to alleviate itching might be required.
If you are not on any drugs, then drug reaction is ruled out.
If allergy (red diffused hives on entire body including the face), then appropriate antihistamines need to be given or corticosteroids
Other possible causes of your itchy rashes is prurigo
(require hydrocortisone cream
), dermatitis/eczema, systemic diseases such as diabetes
, kidney diseases, autoimmune diseases etc.
Scratching might cause superinfection
of the rashes and hence a course of antibiotics.
I recommend consultation with a dermatologist as you must have noticed that skin diseases can be problematic in diagnosing by most doctors.
Hope this helps