Hi, I think there seems to be a common thread with all these hormone medications.  Hot flushes, sleep disturbance, huge appetite, feeling sick etc.  I took Letrozole (for endometrial cancer) and had quite a few symptoms for about 3 months.  I have now been taken off it as it stopped working and about to start on Provera.  I know a lot of post menopausal women with breast cancer do take Letrozole now.  

I do hope you can sort this problem out.  It's worth talking to your oncologist about it.