The decision to cut short Bell's time with the Skrill Premier League side was taken because of the injury sustained by Mitch Hancox at the weekend in Blues' 2-2 draw against Middlesbrough.
Hancox injured his knee
during the closing stages of the game and it will be assessed to see the extent of the damage.
Bell signed off his spell at Nuneaton on Saturday by helping them to a narrow 1-0 away win at Hereford United.
That result saw Nuneaton move into fourth place in the table and a play-off spot.
During his time with the Boro, left-back Bell made a total of 19 appearances.