The 21-year-old defender was stretchered off shortly after half-time in Town's 3-0 win over Newcastle United's Under-21s in the EFL Trophy.
Sears spent the best part of a year out with an ACL injury in 2019 and was making just his third appearance back in the side. Brad Walker also came off injured with a bang to his knee. Sean Goss missed the tie with a rib injury.
Sam Ricketts said: "He's gone off to hospital and when we get some feedback from there we'll know the severity or hopefully lack of severity of the injury.
"Searsy fought back from injury and unfortunately adds another name to our ever-growing list of freak injuries. His foot and ankle got stuck in the turf."
Dave Edwards is set to spend up to seven weeks on the sidelines with a stress fracture of the ankle.
The midfielder started the season opener at Middlesbrough in the Carabao Cup, but has missed Town’s opening two League One clashes against Portsmouth and Northampton Town.
The 34-year-old’s injury is part of a growing list of absentees for Town boss Sam Ricketts to contend with in the early weeks of the campaign.
Edwards felt in good shape after an encouraging pre-season and Ricketts feels the stress fracture was an unfprtunate and unlikely injury.
“Edo has a stress fracture near his ankle,” Ricketts said. “An injury that you have a 0.3 per cent chance of suffering – so he’s unfortunate that this has happened.
“Apart from that, he’s in great shape and he had a great pre-season. We are looking forward to having him back as soon as that heals.”
Rekeil Pyke will spend a period on the sidelines with a thigh injury. Josh Daniels (ankle) and Ethan Ebanks-Landell (head) also missed the tie.
The Town boss cursed his side's fortune on the injury front, adding: "Impact injuries are frustrating. We're not having the rub of the green. Hopefully the tide will turn because it's amazing the injuries we're getting.
"They are from freak situations. It is what it is. We can't shy away from it, we just have to get players ready.
"What it does do is give young Tom Bloxham the chance tonight, Nigel (Aris) on the bench and there's a couple more waiting in the wings as and when the time is right.
"We're not getting muscular injuries. We worked really hard at that, which is one of the most frustrating things.
"These aren't players ripping hamstrings. We've managed that situation superbly, Andy Johnson and the staff have been superb at minimising the risk of those injuries."