The Cod Army were forced to play with a lone striker at Exeter on Saturday with Jon Parkin, Andy Mangan and Steven Gillespie all sidelined.
"I don't know if we'll get them back in the short term," he told BBC Sport. "Me and the chairman and the scouting staff are working hard to try and bring in the right type of player to play up there and maybe help us out.
"I've got a fantastic scouting staff and we always plan for this. We'll make sure that the person that comes in, if we decide to do that, is right."
Mellon's last loan signing was former Scotland international Barry Ferguson, and the Town boss has hailed the midfielder's impact since his arrival at Highbury.
"He's an absolutely top drawer player and top drawer guy and we're delighted to have him at Fleetwood and we just want to keep picking up points with him in the team. A manager can't have enough of those sort of players in his group."