I underwent mastectomy last year. I was 50 yrs old then, and is still having my mentrual periods. My doctor prescribed arimidex, and had been telling her that i am not yet postmenopausal. She said it is ok, since i am in my perimenopausal stage. Anyway, i am now experiencing terrible back pains. I find standing, walking, and sitting for at least 10 minutes so uncomfortable. i really hurt all over. Is arimidex really causing all the pain? i do not feel depressed though, but i do have anxiety attacks. My weight on the other hand has not increased, and i am not bothered by hot flashes. I do suffer from lightheadedness most of the time though. My main concern is the pain, i just can't seem to enjoy my life. can anybody advise me what to do? should i just stop taking any medication? I was daignosed stage 1, er/pr positive, lymphnodes negative.