Brown patches on the elbows and other friction areas could also be a sign of Addison's Disease. That's a malfunction in the adrenals. Please have that checked too!

Some symptoms include:
The onset of the illness is gradual with progressive tiredness and easy fatigability, weakness, loss of appetite, nausea and vomiting, weight loss, brown pigmentation of the skin and mucous membranes, low blood pressure and occasionally low blood sugar (hypoglycaemia).

http://www.teleplexus.com/Comp_Article_AD.html


Anyway, I would try to see an endocrinologist; I would say the problems are probably hormone related.