I am still NWB, although I see the doc in 10 days so I hope to start walking then.
I get some odd foot cramping from time-to-time. My physical therapist thinks it is because muscles get so weak that any time they are asked to work (in my case ROM exercises) they will feel strained and irritated. She seems to think as muscles get worked and stronger, this will ease and go away.
I wonder if you are experiencing the same.