Hey mjay. I have been on Anastrozole since last December and my hair is also thinning and lanky. I noticed aches and pains shortly after taking it and my oncologist suggested I give it a two week rest to see if that helped. It didn't. I went back on it and after consulting with several doctors found out I had developed PMR (polymyalgia Rheumatica) for which I am now taking Prednisone. (Many posts about PMR on this board from Mayo). No one seems to know how PMR develops, but I personally think that chemo and all the chemicals associated with breast cancer lower your immune system so other nasty things creep in. Just my opinion. Good luck with your diagnosis of Gilberft's.