Spondylolysis-Stress Fracture (12 yrs old)

[ruano5846]

My son just turn 12 and started feeling back pain in his right side lower back only when swinging from the left side(he's a switch-hitter.) It was basically while batting practice after 10-11 swings. No pain while throwing or doing other things. I took him directly to a spine orthopedist Dr. He ordered a CT scan and a bone scan. I was almost sure he had spondylolysis. To my surprise both tests came negative. So, Dr. ordered an MRI. MRI report says: L5-S1: marrow edema in the rigth pedicle and pars consistent with a stress fracture. CT correlation helpful.

Below there's some history:
Late April - started feeling some mild pain during batting practice as a lefty. (I decrease intensity of practice).
June 2 - I decided to stop playing him.
June 11 - Bone Scan and CT scan performed (both negative). I requested and saw the final reports.
June 20 - MRI performed (marrow edema on left par)
June 22 - Dr. ordered an LSO custom made for 6 weeks.(will have it for Tuesday).

Dr. says is only a stress reaction but he place him in a brace for 6 weeks.
Somebody told me that is possible that the CT Scan and bone scan were made too soon and that the fracture can be seen later. Is that possible? He started feeling pain late April and the CT and bone scan were June 11. I think that those 7 weeks is enough to see the fracture on the CT scan? Right?