Sound similar to what I have. I've been taken Anastrozole for 8 months. The first 4 was uneventful. Then I started to experience finger stiffness when I woke up in the morning. The stiffness went away in a few minutes after I exercised. Now it take longer and I have hard time closing my fingers. I also feel pain in my feet when I get up in the morning. The pain seems to radiation from the ankles and the heels. So I usually sit on my toes to stretch the feet and the achilles before I start walking. I feel like the little mermaid in the morning. Every step is painful but the pain go away after a while. I think all those are side effects of Anastrozole. Like you, I've been living an active life: hiking, running, swimming, etc. I'm going to stay with this med until it becomes unbearable. Good luck to all of us!