Born in Leek, Staffordshire, Fox began his career with Exeter City, where his father Peter was player-manager, before joining Manchester United in July 2000.

However, he was unable to break into the first-team and spent time on loan with Belgian club Royal Antwerp and Shrewsbury Town before making a permanent transfer to Blackpool in 2006.

After Peter signed for Exeter City in 1993, the family moved to Devon and David joined the club's youth system.

[3] In his first season with Manchester United, Fox was a regular in the under-17s, playing in 26 out of a possible 27 matches in the FA Premier Academy League and scoring seven goals.

He also made one appearance in the FA Youth Cup, coming on as a substitute for Gary Sampson in the 8–0 fourth-round win over Scunthorpe United, as well as making his debut for the under-19s in a 2–1 defeat away to Wrexham on 17 March 2001.

[4] The following season, he was farmed out on loan for six months to Manchester United's Belgian feeder club, Royal Antwerp, where he made 11 appearances, all in friendlies.

[4] After seven matches of the reserves' season, on 7 October 2004, Fox was signed on a one-month loan by League Two side Shrewsbury Town.

Fox made his debut for Colchester in the opening game of the season on 8 August 2009, in their 7–1 away victory over Norwich City, in which he scored direct from a free-kick.

[10] Following his release from Norwich, Fox had an unsuccessful period training with League One side Preston North End, before rejoining his former club Colchester United on trial.

[12] He made his second debut for the club on 11 October, starting in the U's first home win of the season as they defeated Fleetwood Town 2–1 at the Community Stadium.

[14] Fox scored the first goal of his second stint with the club from a free kick in Colchester's 3–2 defeat to Crawley Town on 14 March.