Pain in upper back neck and headaches

I have been on Letrozole for nearly 4 months.   started with Cipla then Sun Pharmacy, then Accord and now back to Sun Pharmacy.  I was fine for the first 3 months with no symptoms at all.  Then over the past month I have been experiencing a pain in my upper back, neck and a headache.  I was wondering if anyone else has these symptoms.   Some days I feel really awful and having another one of those days so thought I would ask.   

Hi Sue , sorry you are having a miserable time . May be worth talking to your breast care nurse about your symptoms , there’s always a possibility that you’d pain may be completely unrelated  . Changes in brand do really seem to affect some people if you can find one that agrees with you ,you may be able to get your GP to specify a brand on your prescription but this also depends on the pharmacy being able to source that brand .Hope you feel better soon.

Hello Sue,
I have been having some neck and pains in back of the head recently. I have been on letrozole Sun since October.
Have did you resolve your pain issues?