My Boyfriend Aged 67, Has Had Severe Pruritus (no Rash)

My boyfriend aged 67, has had severe pruritus (no rash) since 2003 after having undergone Brachae Therapy. He has been thru the gambit of many tests and still it remains a mystery. He has even been to expensive private clinics and they basically told him that the medical establish has failed him as they are stumped. I am thinking that there may be a kidney or liver connection or maybe something to do with his blood. Any advice on what we should do next?