The Scotland international has continued to play whilst struggling with the injury but was forced to miss Saturday's 3-0 win over local rivals Newcastle.
|7/2||Sunderland are 7/2 with PaddyPower to beat Hull City with both teams to score|
"It's affecting him more than I thought," the Uruguayan told The Sunderland Echo. "I'm a bit worried about it.
"We're analysing it with the medical staff but we're going to have to make a decision one way or the other.
"We'll have to look at the games ahead and the chance of rest in between but we'll beed to make a strong decision."
Poyet paired Fabio Borini and Jozy Altidore in attack in the win at Newcastle, while he can also call upon January signing Ignacio Scocco and England Under-21s international Connor Wickham, who scored eight goals in 11 appearances while on loan in the Championship with Sheffield Wednesday earlier this season.