Guthrie was forced to miss Tuesday night's 3-1 defeat at Bournemouth after injuring himself during the warm-up.
Manager Nigel Adkins said: "Danny pulled out 10 or 15 minutes before the game, there was no suggestion of it beforehand.
"He had a similar injury earlier in the season and was out for a while. Whether the pitch at Charlton had something to do with it, I don't know, the previous time was after a heavy pitch at Brighton, but again I don't know.
"The scan will determine the grade of the injury. Hopefully it's not a strain, it could take 21 days to clear up, and the domestic season finishes on May 3 so any injury now is running it close."