Bobby Hassell returned in midweek and played the full 90 minutes at Derby with the aid of a painkilling injection but the 29-year-old has now been told to rest and Robins is considering his options.
He said: "Bobby went for an ultrasound scan and will need to rest for a couple of weeks.
"We have the Slovenian lad (Suad Filekovic) in training with us and he has looked very decent and we will look to make a decision on him soon.
"We might look to do something else as well and there could be movement on that in the next 24 hours."
Source: Team_Talk