LAKE FOREST – Before the bye week, the biggest question about the Bears’ No. 1 quarterback’s health was about his left shoulder.

After Justin Fields got through that injury, now he’s dealing with another ailment as his team returns from the off week.

At his news conference on Wednesday ahead of the Bears’ match-up with the Eagles at Soldier Field on Sunday, head coach Matt Eberflus said that the quarterback is dealing with an illness that will keep him out of Wednesday’s practice.

He wouldn’t get into details about it, only to say it’s “day-to-day,” but he was optimistic about his chances of starting against Philadelphia in four days.

“I think he is improving. I think he’s feeling better, and it’s looking positive,” said Eberflus when asked about Fields’ status for Sunday, mentioning that he feels good about his chances of playing Sunday.

Fields has only missed one game this season and that was the Week 12 contest against the Jets at Met Life Stadium. That was due to a left shoulder separation and partially torn ligaments suffered on the final drive of the Bears’ Week 11 loss to the Falcons in Atlanta.

In Week 13, Fields returned to the lineup to face the Packers at Soldier Field, throwing for a season-high 254 yards on 20-of-25 passes with two interceptions with 71 yards rushing on six attempts.

The quarterback had a 56-yard first quarter touchdown run, one of three that he’s had over 50 yards this season.

So far in his second NFL campaign, Fields has completed 61.7 percent of his passes for 1,896 yards with 13 touchdowns compared to ten interceptions. He’s rushed for 905 yards on 128 carries (7.1 per attempt) with eight touchdowns.