"I banged my shoulder and now there's a little bit of bone sticking out of it, that's all I know, the physio knows a bit more," Cox told the Western Mail
"I've seen a specialist, I'm alright, just got to get on with it. I did used to strap it up before a game, but I was in too much agony afterwards.
The veteran defender opened his City account on the weekend with two goals in City's 3 - 0 win over Stoke. He is in the team becuase of a hamstring injury picked up by Glenn Loovens.
"Glen was playing really well and Pursey was playing really well and I was sitting there on the bench," he continued.
"You get your opportunity and you've got to take it, and that's what's happened, it's disappointing for Glen as he's had a good season, but everyone's got to play for their places."