Why would my fore arms and lower legs hurt down to the bones i have dry mouth and a itchy head i was tested for auto immune diseases it came back neg?

Arm & leg pains: If you've been evaluated by a rheumatologist and autoimmune disease has been effectively ruled out, I would consider fibromyalgia as a possible cause of your symptoms. Are you aware of any tender points in your body? Another possibility is a variant of restless leg syndrome. Do you get relief on moving? I recommend consulting a rheumatologist but if you've already seen one, revisit him/her.