Chronic Itching that cant be stopped

My 15 year old teen has had chronic itching for over 5 years.  We have seen two Dermatologists (different practices) a family doctor and an allergist to no avail.  Both Dermatologists have have said its eczema but there has been no change in the condition despite their treatment.  NOTHING stops the itching and its almost impossible not to scratch.  We have tried the following prescriptions to no avail multiple times
Cetirizine
Clobetasol propionate foam
Derma Doctor KP Duty
Differin (adapalene gel) for acne
DIPHENHYDRAMINE
Elidel (pimercrolimus cream)
Erythromycin
Fexofenadine
Fluocinolone Acetonide cream
Fluticasone Phopionate ointment
Hydrocortisone 1% Cream
Hydroxyzine HCL 25MG
Loratadine
Mederma cream
Mimyx Cream (general hydration)
Mometasone Furoate Cream
Polymixin D Sulfate, Bacitracin zinc, Neomycin Sulfate, Pramoxine HCL
Prednisone
Synemol (Fluocinonide Cream)
Triamcinolone Acetonide
Vanicream
Zinc Oxide cream 11%

The Hydroxyzine causes depression and every other topical medication will work for only a very brief amount of time then the itch returns with the same intensity.  It is as if the condition is immune to the medication.  The legs and arms are covered with what look like insect bites 5-10 mm in size and scratched open in the center.  The worst areas are on the back of the upper thigh where the skin is red and thickened 10 cm in size.  Basically dry but will weep either blood or clear liquid.  The child cannot concentrate and is a slave to the effects of the itching.  The Allergist says no specific strong allergy was found just the usual (Dust, pollen etc) but none severe.  The dermatologists have said they have no idea what to do next.
We have tried EVERY over the counter medication, special baths, laundry detergents to no change.
I welcome ANY suggestions...

[carcrazy]

Is he having any other symptoms...even if they don't seem related? Something he may not have wanted to mention or didn't think relevant.. Diarrhoea? regular upset stomachs? Its just that the spots you describe sound similar to what my mum has with her coeliac disease, might be worth considering if there are any stomach symptoms.

Other than that I really cant think of anything that the dermatologist hasnt already covered but you could try food elimination. Firstly cutting out all the foods that commonly cause problems and working your way down

Just as an afterthought have you tried eurax, its an anti itch cream and i've found it helps break the itch scratch itch cycle when I have a flare up

[v194]

No other health conditions or symptoms are present.  No stomach problems either.
I will look into eurax. Thanks