Warburton suffered the injury while captaining Wales against France and was taken off at half-time by coach Warren Gatland.
It was initially reported that Warburton could be out for the rest of the season but an initial MRI scan proved inconclusive.
The 23-year-old Blues flanker has since scheduled an appointment with a specialist where he hopes to find an answer as to how long he'll be out of action for.
"Not much showed up on it," said Warburton of the initial scan. "There is a bit of concern because I am still in quite a bit of discomfort.
"I am seeing a specialist and I will find out more then. The MRI scan did not show any soft tissue damage.
"It may be that it is more complicated than that, such as something to do with nerves, which would not have shown up.
"I do not know what to think - it could be two weeks, or it could be two months. I hope it is shorter, rather than longer.
"One of the reasons they are finding it difficult is that I cannot recall the incident in the game when it happened.
"If the physios knew when it happened then they could look at the video and see what sort of collision it was and what might have happened to the joint.
"There was a lineout when the ball was overthrown, and Julien Bonnaire beat me to the ball. I went to grab it, but I could not lift up my arm because of the pain.
"I knew then I would have go off at half-time. I have not watched the game back yet, and I will have to do so to see if it triggers something in my memory."
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