My legs are giving way!

Got up from the wheelchair today after taking a wander around the hospital, and crumbled to the floor. It was totally without warning. It's as if my brain and my legs are not talking to each other anymore, or my brain thinks my legs are strong enough to sustain my body weight but the legs definitely disagree. Nothing's broken, maybe just a bit of confidence and pride at the least. Oops..the nurses had to fill in an incident report...