The Black Cats midfielder has been struggling for some time with the problem, and visited a specialist earlier this week.
Manager Martin O'Neill said: "He went to see the specialist and he has given him an injection. At this moment, he is hoping in the next couple of weeks that that would cure things. But if it didn't do, then we might have to have another look at things, so we will see how it goes."
Asked if surgery might be needed if the injection does not solve the problem, O'Neill replied: "That has been mentioned, but we will see.
"I wouldn't start to draw too many conclusions from that at the moment, but that might be the case."
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