The midfielder suffered a nasty looking ankle injury at Motherwell over the weekend when he was forced off the pitch in the 55th minute.
The bottom of the table club were beaten 2-1 despite taking the lead and manager Gary Locke told the Edinburgh News: "That's the way things are happening for us at the moment.
"We'll wait and see how Callum settles down and the physio will look at him as well.
"Hopefully, it's not too serious but it certainly looked like a bad one when he went over on his ankle."
There is also concern over Billy King, who was unable to play at Fir Park on Saturday - the 19-year-old midfielder watched the match from the stands with his sore foot in a brace.
And King added: "Billy has a wee problem with the sole of his foot. It's getting worse each day with the more impact he puts on it so I think the only cure is rest. Hopefully that will settle down over the next few days.
"Our physio is hoping that just a few days off it will see it settle down. It's like a bruise. If you keep hitting it, then it won't get any better. We had to leave him out on Saturday and hopefully he'll be back training at some point during the week."