The on-loan from West Ham centre-back picked up a neck injury during the 2-2 draw at Vicarage Road at the weekend and has returned to Upton Park for treatment.
"Calum heard a crack in his neck and he lost the sensation in his fingers and he is in the hospital now," manager Aidy Boothroyd said.
"When it is a neck injury you have to get him off the pitch straight away and we hope it is not too bad."