Sorry to hear that Phillip, esp. when the Enbrel was working so well. I've never had quire the response to a drug that you are asking about, but I do know all too well about the ankle, foot, and wrist pain. Well before I was on Enbrel, my AS followed the progression you discuss in your post--moving from the back and hips to the smaller, peripheral joints. Only my fingers truly remain unaffected now, which is very good since I'm an editor. In my opinion, I doubt the Enbrel is to blame for any new pain--it just sounds like AS being AS to me. I don't know if that answer is better than one saying that the Enbrel was the culprit--only you can decide that!
Brad