From what I've found out, here in the UK, these infusions are done once a year for three years initially. Treatment is then reviewed.
The most common side effect appears to be some flu like symptoms...chills, muscle aches, slight fever...for a couple of days after the first infusion, easily treated with over the counter meds, and for this reason it's recommended that you don't plan to do anything in those days.
There's no mention anywhere about cramps.
I take oral alendronic acid once a week for osteoporosis and have wondered about asking about the infusions myself. Can I ask why you're having infusions rather than oral meds?
I forgot to say, the infusion is called zoledronic acid.
Bunty x