Terriers manager Lee Clark told the club's website: "That's not just a blow for us, but it's bitterly disappointing for Robbie.
"He's had a really stop-start beginning to his Huddersfield Town career."
Clark added : "Robbie's recovery from a thigh injury has been slower than we first though.
"As a result he has had a scan at the hospital, which revealed a second degree tear, this means he could be out for up to a month."
Fellow forward Lee Novak will also undergo a scan on the shoulder injury on Wednesday, which he picked up in the win at Oldham.
Winger Anthony Pilkington will rejoin training on Wednesday after quickly recovering from his hip injury, also picked up at Boundary Park.