The defender has missed the Robins' recent matches against QPR and Preston through suspension.
A niggling rib problem means his absence could now continue for the trip to Nottingham Forest on Saturday and for the home game against Ipswich on Bank Holiday Monday.
"Louis has got a rib injury and he has been suffering with it for a little while actually," manager Gary Johnson told the club's official website.
"A scan during his suspension showed some ligament damage, but it wasn't too much of a concern as he was already unavailable to us.
"However, the other day he turned sharply in training and felt a problem. He keeps suffering a pain every now and again, which is a concern and we will have to keep an eye on him ahead of the Easter games."