The 32-year-old started against Wigan Athletic, Cambridge United and MK Dons following his January switch from Plymouth Argyle.
Since then he had been restricted to four appearances off the bench – despite Rovers’ continued struggle for goals.
Boss Gary McSheffrey rolled the dice at Fleetwood, pairing Agard with fit-again Jordy Hiwula who was also making his start since January 8.
But the experienced striker’s afternoon was cut short early in the game and he was replaced by Reo Griffiths who himself has been nursing an Achilles tendon issue.
"He felt a bit of stiffness in his hamstring,” said McSheffrey.
"He didn’t really feel it go at any point but bending his leg he feels something and it feels a little bit heavy now which sometimes is a sign of a pull.
"I’m disappointed for him. He’s worked hard and he’s had to be patient. He had a good hour the other day in a reserve game at the Eco-Power.
"We’ll wait and see what the physio’s diagnosis is but, in general, if you come off after ten minutes with a hamstring it’s probably unlikely you’re going to be available for the next couple of games.”