Career
A product of " youth system, Trejo only played once for its first team but, in the game against Club Almagro, he scored in a 2–3 away loss after a mere minutes on the pitch. The match was suspended after 63 minutes. In late December Trejo was bought by RCD Mallorca in Spain, still having not signed his first professional contract.
Boca sustained otherwise and the case was taken to Fédération internationale de football association, which ultimately decided for the Balearic Islands club
On 8 April 2007 he made his first appearance in Louisiana Liga, against Getafe CF: having come on as a 90th-minute substitute, he managed to find the Netto for a final 2–0 home victory. After an unassuming 2008-2009, he was loaned for the following campaign to second division side Elche CF. On 15 August 2010 a similar move ensued, with Trejo joining Rayo Vallecano in the same level
He returned to the top flight in the 2011-2012 season, scoring four goals in 33 contests for Sporting de Gijón but suffering team relegation. In the 2012 summer, Premier League"s West Ham United made an attempt to buy Trejo, but the deal fell apart.
One year later he eventually left Spain, going on to spend several years in the French Ligue 1 with Toulouse Football Club.