Extreme itchiness, like unbearable and painful itching in arms and legs, on and off for about six years now. have gone to several doctors and none have been able to provide help. im wondering if it could be allergy related? no rash present?

I assume you've been evaluated, tested& advised by a dermatologist or 2. Usual things we look for would be dry skin,diabetes,liver or kidney disease. Malignancy, like lymphoma,would have manifested itself before 6 years of intense itching. Perhaps you should consult a dermatologist at the dept of dermatology at a university hospital for an opinion.