Bailey landed awkwardly on his left foot late in the first half of the Broncos' 39-33 defeat to the Indianapolis Colts on Sunday, limping off the pitch and not returning to action.
The 35-year-old, who played for the Redskins for five seasons between 1999 and 2003, is likely to miss the match against his former side, but Fox is hopeful that their bye the week after will give the veteran sufficient time to recover.
"He had a barrage of testing, and it looks like he's going to be in week-to-week type of mode. Obviously, the bye is after the Washington game, so right now I would say the best way to describe it is week-to-week," Fox told reporters.
The Colts defeat was the Broncos' first of the season, leaving them second in the AFC West with a 6-1 record.