Tomkin’s foot became swollen and sore and was X-rayed last Saturday at Salford Royal.
He has since had extensive investigations including CT and MRI scans which have confirmed the severity of the injury.
Tomkins will have investigative surgery early this week with repair performed as necessary.
O’Loughlin’s injury on Friday is highly likely to prevent him from playing in either the Play-Offs semi-final or the Grand Final if Wigan get there.
O’Loughlin sustained a calf muscle injury during the warm-up on Friday.
Ian Lenagan, Wigan Chairman, said: “This season has thrown up bigger challenges with injuries than ever before, yet I’m proud to say we are still fighting fiercely and successfully as shown by the 12-man victory over Warrington last week and in Friday’s performance against Catalans to qualify for a home semi-final.
“Currently, Wigan has only 20 players available from a First-Team squad of 35 but there is a tremendous spirit and confidence amongst this Wigan group that thrives in adversity.
“That character and resilience, plus the ever-improving performances in defence – and growing effectiveness in attack – of our remaining First-Team and Academy players lays a great platform for the crucial next two weeks.
“Despite all of the challenges that the club have faced this year I, Shaun Wane, Kris Radlinski and the First-Team squad believe that we can defy the odds to make this an excellent season-end for Wigan.”