The Norwegian international underwent a scan on his back and hamstring after complaining of pain during the closing stages of Saturday's win against Crewe but the results have proved inconclusive.
Bakke is unlikely to train before the weekend trip to Preston but the good news is that he has not suffered a tear to his hamstring.
But United are concerned about the nature of the problem and why it has flared up.
Bakke returned to the starting line-up against Reading on Easter Saturday and has played in the last three games.