Cunningham went down off the ball in the first half at Deepdale and was holding the lower part of his left leg.
Team-mate Patrick Bauer was straight over to check if Cunningham had hurt his Achilles - Bauer suffered an Achilles injury in December 2020.
It's a calf injury which is feared but it will need the scan to give a proper diagnosis.
North End manager Ryan Lowe said: "Greg has been fantastic for us, he has got that bit of quality in the top half of the pitch.
"Anytime you lose any player it is a blow.
"We will assess him tomorrow, he'll have a scan and we'll go from there.
"Greg has waited for a long time to get into the team and cement his place and he's certainly been doing that.
"I'm not going to say how long it will be but it doesn't look good because he wouldn't have come off the pitch if it was.
"He's got the right medical team around him, I think it was his calf. If it's a muscle strain it's four, five, six weeks or something."
Cunningham was able to walk off the pitch and later left the ground in a protective boot.
Lowe felt North End deserved more from the game than the point they got, with his side looking the most likely going forward.
He was convinced Emil Riis should have had a penalty when he went to ground in the box with seven minutes left.
Lowe said: "It should have been three points. I've seen the replay back and it was definitely a penalty.
"Sometimes you get them, sometimes you don't.
"I thought the performance, especially in the second half, warranted three points.
"We started well and then faded off a little bit in the first half. Huddersfield are fifth in the league so give them some credit.
"To limit them to one shot on target was good on our behalf but again it was a bit of luck missing at the top end of the pitch, .
"We had so many chances, created a lot of opportunities. It's a point and another clean sheet but the quicker we turn them into three points, the better a team we will be.
"I thought we were very good in the second half.
"It was just in the last little bit wasn't it? That comes with work on the training ground and the belief of when to take that shot.
"There was that one when Cameron Archer dropped their centre-back - dropped his shoulder, slips the lad but then has that extra touch and puts it over the bar.
"Usually they are going in the bottom corner. You can't fault the effort of the group. but I just want a little bit more belief, someone having a shot from the edge of the box.
"We have come along way in a short space of time."