He gave an FA interview after the game, plus I have not seen a single report on his injury. I don't think it's serious. Maybe a week rest should be given even if he is fit so that he doesn't get burnt out
http://www.thefa.com/news/england/2015/nov/chris-smalling-spain-v-england-fatv-reaction
http://www.thefa.com/news/england/2015/nov/chris-smalling-spain-v-england-fatv-reaction