"Robbie's ankle came up like a balloon and he is having scans," Dave Jones told the Echo. "He was tackled during training and suffered an impact injury.
"It's a big blow for Robbie because he has worked hard to regain fitness.
"He has been looking good and feeling sharp in training, but these are not the best of times for him.
"Now he must work his way back again and he's up for the challenge.
"We won't know the extent of the problem until the medical people have looked at the scans."
Fowler is only just back after a hip injury.