With Somerset currently taking on Nottinghamshire in their final match of the County Championship season, the opener is yet to score a century during the current campaign.
Caddick, who played with Trescothick for Somerset and England, believes that the 37-year-old's stint as captain has affected his batting.
"The pressure that he's carried this year needs to be removed," Caddick told BBC Somerset.
"As far as I'm concerned, his position in the team as a batter has to come first. If he steps away from the captaincy and concentrates on his batting then he needs to make that decision.
"We want to continue seeing the best of him and see him scoring hundreds of runs at the County Ground."
Trescothick has an average of 28.21 in Division One this season.