"He's also had X-rays on his neck. I'm praying it's just a couple of weeks because he's a big player for us.
"Until we get the scan results we have to wait and see. He's been a big part of it. He'll be missed."
Alan Julian, who is on the transfer list, was drafted into the side for his first league game since August and the club did not name a keeper on the bench.
Julian produced an impressive display but saw his side lose 2-1 against Huddersfield.
Stimson said: "Alan was outstanding. A couple of free-kick saves were excellent and his kicking was spot on.
"He's waited a long time for this opportunity. He knows if he wants to keep it he as to grasp it, and he couldn't have done a lot more.
I am sure if he takes his opportunity it will be hard to put Simon Royce back in the side when he comes back
Mark Stimon on Alan Julian
"One save from point-blank range was something I would have clapped Simon Royce for had he been here.
"He wanted a chance and it was hard to give him a chance because Simon Royce was playing so well.
"Alan's a top goalkeeper and it was just unfortunate for him that Roycie came back from the summer with the bit between his teeth.
"I am sure if he takes his opportunity it will be hard to put Simon Royce back in the side when he comes back."
Royce joined the Gills initially on loan in April 2007 before making his deal permanent and is currently in his 19th season in professional football.
Stimson also confirmed that midfielder Curtis Weston missed Saturday's game for personal reasons but is expected to return for this weekend's home game against Stockport.
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