Possible Arimidex side effects?

[KeyserSöze]

My E levels went from very low in the range to very high in the range and my current clinic gave me an Arimidex pill. Since then, I have been having lower abdominal pain (somewhere between slight cramp and abdominal strain) that is mainly on my left side, but at times on both sides. My hips and knees are also super tight and sore.

I am in the process of getting my treatment switched over to Defy, but does any of the above make sense as potentially being related to the Arimidex? Thanks.