I also experienced severe and persistent heartburn after taking Actonel and Fosamax.  My doctor wanted me to stay on some form of these meds, but my intuition told me not to.  I started to do leg exercises (because my worst density was in my hips) and when I had my next bone densitometry the following year, my t-score had improved.  I really believe that exercise is the key, at least for me.  Please do yourself a favor and search the Internet for more information.  There are lots of ways to supplement your diet and change your lifestyle that will complement medication or eliminate the need for it.  Heartburn is also the most obvious of side effects of this class of drug.  Listen to your body and educate yourself!  Knowledge is power.  Best of all wishes to you!