He missed Saturday's trip to Stevenage with the problem, which he suffered when a Tranmere player fell heavily on him the previous Saturday.
He was not substituted during the game, but the ankle swelled up afterwards. He was kept out of training again early this week, and will finally have an x-ray this week to check there is no serious damage.
"He will go for a scan at some point this week. It's just a precaution really, just to make sure," said manager Alan Knill, speaking to the club's official website.
"Karl didn't train on Monday and he's going to have a scan on it, but I spoke to the physio and he doesn't think it's too bad."