Rovers will be without attacking trio John Marquis, James Coppinger and Alfie May for Tuesday night's clash with Portsmouth.
Marquis picked up his fifth booking of the season in the 1-0 defeat at Charlton Athletic and will serve a one match suspension.
James Coppinger suffered a calf injury at The Valley which forced him off after only eight minutes of play.
And Alfie May may need an operation on a calf problem which ended his afternoon in the second half.
With Andy Williams already ruled out of Tuesday's game - and potentially longer - Rovers have only one recognised senior forward in Liam Mandeville available.
"There are three changes that will be definitely made for Tuesday," Ferguson said.
"John is suspended. Coppinger and May are out.
"That gives me a wee bit of a problem up top.
"Coppinger has done his calf after six minutes. I think we missed him because he creates so much from that part of the pitch.
"Alfie has been feeling his groin for a long while now.
"He is definitely going to be out for Tuesday and there's the possibility he may have an operation on that.
"And John is suspended after five bookings."
Ferguson was furious with his side's performance in the defeat at The Valley. To read his thoughts, click HERE