Holy Cats and Kittens!
This seems to be blog post number 1,600.
Because of the nerve damage as a result of his spinal cord injury, Robb has very limited sensation in his feet.
A few days ago, he was experiencing particularly high level of spasticity (uncontrollable muscle spasms) in his legs, and couldn't figure out why.
It turns out that he must have caught his little toe while putting on his shoes, and completely ripped off his toenail. He literally couldn't feel this, although apparently the rest of his body was relaying the message somehow.
This is one of those glass-half-full or half-empty situations. If Robb could feel his feet, he wouldn't be snagging them on his own shoes. But, hey, at least he doesn't have to endure the pain of a torn-off toenail.