The 19-year-old, who is on loan from West Ham, left Kingsmeadow on crutches after the 2-2 draw against Port Vale on Thursday night.
But an X-ray confirmed there is no fracture and McCallum, who has scored four goals in six games since joining the Dons, could even be fit for Saturday's clash with Burton.
Dons physio Mike Rayner told the club's official website: "The X-ray confirmed there was no fracture. Paul was very sore afterwards and that is always a worry, but hopefully managing the injury well early on has lessened his time out.
"I have spoken to West Ham and they are hopeful that he will back in training come Thursday or Friday."
McCallum's fellow striker Charlie Strutton is back in full training after six weeks out with a knee injury.