Great to hear she is on the mend. it does sound like a posterolateral derrangement. a static position that increase the symptoms would have indicated that there was a block. The ext. in standing would have been to much load to make a reduction. a static supine extension then needs to be moved into a repeated extension in lying to mobilize the segment, perhaps with some simultaneous PA mobs to assist. You cold have started in the shift to reduce the discomfort and is movement improved slowly bring her back to midline. etc etc etc. If that was all to much then some way of tractioning her while passivley extending might have been an option. A lot of possible treatment techniques would depend on the iritability at the time and sometimes extension to soon is to much to take and you need give the client techniques to reduce any associated spasm to being with. This might include pain skiilers. Then get in there