Like you, my IBS was aggravated by Fosamax. I was only able to stay on it for 3 months before I decided it wasn't worth the discomfort. My "bad day" was usually the day after taking the weekly dose. I found myself questioning everything I ate, worried it would bother my stomach. Continual aching in my hips and legs. I too want to protect my bones but at what cost is an excellent question. I took myself off the Fosamax (perhaps not the smartest move) but after two weeks I am feeling better. I plan to follow this thread to hear about others experiences and decisions. I had planned on asking my endocrinologist about Reclast but from your comment, that may not be the way I want to go. Have you been able to faithfully take your weekly doses, despite the side effects?