He has failed to overcome the problem fully, and despite starting nine games this season has only managed one goal - the first in the 2-0 win over Nottingham Forest.
Barnsley boss Andy Ritchie offloaded Conlon after he failed to spark alongside former Iron striker Paul Hayes.
Dublin-born Conlon said: "I am here for three months because with me not being able to play in the two games against Barnsley, it wouldn't have been worth coming for less.
"I haven't had the best of times recently as I had an injury last season and didn't get off to the best start this time round so I haven't played as often as I would like so this is a big challenge for me to get back into the swing.
"I have had plenty of experience at this level and I am looking forward to getting on the goal trail again."