Anne, I switched over from Fosamax to Actonel about a year after starting treatment, which was four years ago. The Fosamax caused me more GI distress than the Actonel did. Unfortunately, in my case, my osteoporosis continued to get worse over the four years, which is why I am now on Forteo.
From everything I've read, Actonel is supposed to be better at preventing bone loss (or maybe it's at preventing fractures?) than Fosamax. I think most doctors prescribe Fosamax because it was the first of its kind.
With respect to your possible adrenal gland depletion, I suggest that you see your medical doctor for testing.
Are you on hormone replacement therapy following your surgery? HRT can help prevent further bone loss.
I do understand your fears about starting on a new med for a condition that seemed to come out of the blue. Pretty soon, it will become routine.
Oh, I forgot to mention that I have not had any GI problems while on Actonel. What's ironic about that is that I already suffer from GERD and IBS! I had those conditions prior to starting on Fosamax/Actonel and they never got any worse.
I hope that you, too, will tolerate it well.