Detroit Lions quarterback Matthew Stafford has officially been ruled out Sunday against the Chicago Bears, the team announced.

Stafford has fractured bones in his back and doctors will not let him play, a source told ESPN.

Stafford was practicing Friday and throwing 60-yard passes, but doctors wanted him to have further testing on his painful back injury, according to multiple sources.

Stafford is now considered week-to-week with an injury that one source said could sideline him for "this week or 3 weeks." Stafford had started 136 consecutive regular-season games entering Sunday, the sixth-longest streak for a quarterback in NFL history.

The Lions will turn to Jeff Driskel, who will make his sixth career start Sunday, according to sources. The last Lions quarterback to start a game other than Stafford was Shaun Hill in Week 17 of the 2010 season.

Driskel started five games for Cincinnati last season and completed 59.7 percent of his passes for six touchdowns and two interceptions

Stafford's injury dates back to last season, when he played through the pain and didn't miss a game, even though those around him knew how much he was suffering.

The pain has been so bad this season that Stafford's status for Detroit's Week 4 game against the Kansas City Chiefs was in doubt nearly up until kickoff, according to sources. He passed for 291 yards and three touchdowns in that game.

The Lions have listed Stafford on their injury report as questionable five times going back to last season, including twice this year -- once before the game against the Chiefs in Week 4, and this week.

Stafford, 31, is fourth in the NFL with 2,499 passing yards and ranks second with 19 touchdowns, trailing only Russell Wilson (22).

Asked about the injury Wednesday, Stafford said he was "fine." He was officially listed as questionable on the injury report and practiced on a limited basis every day this past week.

Stafford's 136 consecutive games is the second-longest active streak among quarterbacks behind Philip Rivers' 218 and trails only Brett Favre (297), Rivers, Eli Manning (210), Peyton Manning (208) and Matt Ryan (163) on the all-time list.

With Driskell in for Stafford, the line has gone from Bears -2.5 all the way to -6.5 at Caesars Sportsbook.

ESPN's Michael Rothstein contributed to this report.