Trott returned from England's disastrous tour of Australia following the first Test in November due to a stress-related illness and took five months off from cricket.
The 33-year-old returned for Warwickshire against Sussex in April but a repeat of his symptoms led to the right-hander taking a further break from the game.
He scored an unbeaten 138 for the Bears second XI in June and reached 106 at Horsham on Wednesday before being caught behind off the bowling of Steve Magoffin.
Trott brought up his century in 224 balls with a four off England bowler Chris Jordan and ended his 242-ball vigil with 14 boundaries.
Trott fell to the first ball of the 91st over and brought lunch with Warwickshire on 247 for six, a first-innings lead of 166 on day three.
- Sports & Recreation