The Rugby Park side were dealt another blow this week when goalkeeper Bell was ruled out for 10 weeks with a wrist injury.
The Scotland international joins striker Paul Heffernan (broken collarbone) and Garry Hay (knee) on the sidelines.
"We have to remain positive, injuries happen at all clubs," said Shiels.
"It's been very unfortunate in that we have had three operations in the one week, but we won't panic.
"There are young players ready to come in and we have a replacement keeper in Kyle Letheren."
Shiels has been encouraged by the arrival of Spanish playmaker Borja Perez.
Borja made his debut from the bench in the 2-1 defeat against Motherwell and may feature this weekend against SPL leaders Dundee United.
"He got a goal in the under-20s this week," added Shiels.
"There is still some way for him to go in terms of fitness, but he's getting there for sure."