Hi Lisa,
The cramping could be from muscle weakness, or it could be that you need more calcium. Some here have found that those cramps are relieved by adding some extra calcium to their diet.
Did you have this sciatic pain before the surgery, or is this new? I had a great deal of hip and leg pain after my hardware removal. It was because of irritated nerves and took a long time to calm down, but it finally did. During that time, I found it helpful to use a cane on that side. There are also pain meRAB specifically designed for nerve pain. Talk to your doctor about it and see if he thinks one of those meRAB might help you.
How are you doing otherwise? Are you sleeping okay? Are you able to walk some even with the pain in your leg?
I wish you the best as you continue in your recovery,
Emily