Jiri Skalak's bacterial infection means he is a doubt for Millwall's visit of Nottingham Forest.
The Czech Republic international missed Boxing Day's 1-0 win over Reading, the third match he has sat out.
Midfielder Shaun Williams is expected to be out until January with an ankle injury.
Striker Tom Bradshaw is also sidelined and could miss the rest of the season with a knee injury.
Nottingham Forest boss Aitor Karanka could make changes after they blew a 3-0 lead with 13 minutes left to draw 3-3 at Norwich.
Defender Tobias Figueiredo may return after missing the draw with a dead leg he suffered in the 1-0 defeat at QPR.
Daryl Murphy, Karim Ansarifard andAdlene Guedioura are all options for Karanka.
Defender Danny Fox returned at Carrow Road after a long-standing foot problem but Michael Dawson (hamstring) is out along with Hilal Soudani and Sam Byram (both knee).