Reclast injection for bone loss caused by letrozole

I am a ten year breast cancer survivor. After taking tamoxifen for 5 years it was recommended that I begin letrozol. My recent bone density scan indicated significant bone loss and so it was suggested that I stop the letrozol and have a reclast injection. I have a very disturbing reaction to the first injection, but was told that it was likely the second would have a less serious side effect. I am wondering if anyone else has had a similar treatment plan and what their experience has been. I am very nervous about having a second injection. Thanks so much.