A collision, apparently. Haven't seen the incident yet. Happened in the first half of Forest v Derby.
He took a knock in the first half, but continued to play, albeit there was only a couple of minutes of the half remaining. Surprised the ref allowed it, but I guess the docs know what they are doing.
Brentford 0-0 Wolverhampton Wanderers 45' +22. That's right, it's 0-0 in the 67th minute of the first half!