Intermittent pain episodes can occur with SM. I have seen things like this happen in my SM dogs.
This may be a one-off episode, if so it may only be necessary to take a detailed note of what happened and tell the neurologist when you next see them.
If it happens again then it would be wise to check & see if her medication needs to be tweaked some more.
Cavaliers......Faith, The Ginger Tank and Woody.
Japanese Chins.... Dandy, Benny, Bridgette and Hana.
Remembered with love......... Tommy Tuppence and Fonzi