Neurodermatitis is one possibility for your symptoms. The only thing that seems to help most sufferers is the application of ice to the area until the itch is diminished. Other treatments include cooling lotions like those containing camphor or menthol, capsacain or local anesthetic creams,amitriptyline and gabapentin tablets and electrical cutaneous nerve field stimulation.
Please discuss this possibility and these options of treatment with your dermatologist. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Sjogrens and Rheumatoid can be controlled through diet because the symptoms can be triggered by the foods you eat. Most people with your condition will alleviate most of the symptoms if you cut out corn and dairy from your diet. Corn is in almost everything so you must be prudent and learn more about it. Don't eat corn chips, breadings, corn oils, etc. Stop eating dairy and corn for about a month and then do not exceed more than two servings that include corn or dairy per week. A little now and then won't hurt. But every day will cause inflamation which will cause your symptoms. Also drink water after exercising up to a total of 8 glasses or more a day (exercise first because this helps the body absorb the water). Your soap and shampoo probably contain sulfites. Try using a glycerine soap. There are a few shampoo's such as Jason's that do not have sulfites. Also take 2,000 mg of vitamin C a day, take fish oil supplements or eat baked or broiled fish twice a week, rub Crisco shortening on the itching areas every morning and night. You'll start feeling better after a week and be cured in two months.