Scans have shown Sterling suffered ankle ligament damage during Saturday’s 4-1 defeat to Nottingham Forest.
The loanee has returned to parent club Chelsea for further assessment and there’s a good chance he won’t play again for the Seasiders.
Stewart, meanwhile, has suffered a quad injury - yet another setback for the midfielder who has only made 11 appearances this season.
Jordan Gabriel wasn’t risked as he’s only just returned from a five-week lay-off with a hamstring injury.
“Kevin felt his quad unfortunately, so he will be missing and will be out,” Pool’s head coach told The Gazette.
“You miss his presence in the middle of the pitch and his athleticism, but I thought Ethan came in and was fine - him and Kenny.
“Kev will be out and Dujon as well, he had a scan and he’s got some ligament damage so it’s a bit worse than what we thought it was going to be.
“He’s not our player so he’ll have to go back to Chelsea and get assessed and we’ll have to decide the course of the action for the rest of the season."
When asked if that is Sterling’s season over and done with, Critchley replied: “I think it would be too early to say it’s the end of his season now.
"As I say, he went back to Chelsea and he’s getting assessed there.
“In the next 48 hours, we’ll decide where he does his rehab and the timeframe for that as well.”