The popular second-row forward will need an operation on his ankle, and that could virtually write-off most of the season.
Allen, who damaged his ankle when he slipped off a ladder, had gone for a second opinion and a new scan.
The upshot was that he needs an operation and is likely to be in hospital within a fortnight to have it done.
Whitehaven director James Robinson said: “It’s devastating news for David who is such an important player for us. It means he hasn’t played a single League One game this season.
“There’s a possibility we might have him back for the Eights but that won’t be for discussion until after he’s had the operation.
“He had been training but any thought of playing were put on hold because of the reaction he was suffering.
“Desperate to get to the bottom of the problem, he went for a second opinion and now he’s been told he will need an operation.”
Robinson has also expressed his disappointment over the injury to Kurt Maudling which will keep him out for about a month.
“Kurt has been making good progress and was in the team for the last two matches," Robinson said.
"To break his wrist at the time, he was making his presence felt and it was a real blow. I felt really gutted for him.
“Kurt has been patient and, when given his opportunity, has shown what a quality player he can be. I’m sure he will come back even more determined to make his mark."
Robinson praised both Maudling and Lewis Brown, the former Salford Academy player, who have played against London Skolars and Hemel.
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