Coach Matt Nagy told reporters Monday the club is "still gathering the facts" and couldn't provide a further update on Fields' status for Thursday's game in Detroit.
NFL Network Insider Ian Rapoport previously reported that initial X-rays on Fields were negative. The belief is he suffered bruised ribs. Chicago is conducting additional tests on the rookie QB.
The Bears listed Fields as a DNP in Monday's estimated practice report.
Fields exited Sunday's loss early in the third quarter after taking a hit on a scramble. Nagy said Monday he was unsure if the QB suffered the rib injury on the play or it was the cumulative result of multiple shots. Fields was sacked twice while going 4-of-11 passing for 79 yards and four rushes for 23 yards.
With a quick turnaround to the Bears' Thanksgiving game versus the Lions, Dalton would be in line to make his third start of the season, and first since Week 2, if Fields can't go.