The full back picked up the injury at Newcastle and had to be taken off, at the moment he is undergoing tests as specialists try to see how bad the damage is.
And while boss Tony Pulis waits anxiously on news, he does warn that the player has played his last game of the season, especially as this new problem has come so soon after making a return from a two game absence,
Pulis said: "He actually feels better now than when he came off on Saturday, but it's still bad enough to send him for a scan on the hamstring, which will happen today.
"We'll obviously wait to see what the results bring before deciding how to go with Andy, but time is clearly running out this season."