It sounds like Reclast might have caused the back issue, and I say that only because of anecdotes here, so check with your doctor on this.

If you do Reclast, maybe you can request a lower dose (I read that 2.5mg or half dose is as effective as 5mg and my doctor confirmed this last week). I am going to do 1mg and my doc said I can do it every 3-6 months. He also ordered IV hydration and a slow infusion and told me to take tylenol the day before, the day of before and after infusion and at bedtime, and the next day. Maybe some of this info will help.

I hear you about persisting!! I did letrozole, Tymlos, now Evenity and going on Reclast soon. For me, the side effects of the aromatase inhibitor improved over time and walking more than 30 minutes along with tai chi helped. It's tough!

ps My Reclast regimen is for bones to "lock in gains." And I have not been on letrozole since 2021. Your doctors can tell you if the lower dose is effective in the context of an AI. But the hydration, slow infusion and tylenol might still be helpful.