Butt cramp since day after surgery (Photo)

I have a what it feels like a baby " Charlie horse" in my left. It cheek. And it's strong when I'm standing still, a little relieved when I walk. Don't feel it at all when I'm laying down. My after care nurse said it's normal and I need to walk more. She felt my butt nd said as long as it's. Not being felt in my actual butt tissues then I'm fine be it's in the muscle so I need to walk. What do you think?