Dear Min_i_way, hello
It is possible that your wife had developed Vasovagal attack, while at the nail saloon.
In this the patient can develop unconscioussness due to stimulation of Vagus nerve
,resulting in fall. Due to fall, circulation of blood increases towards brain and the patient regains conscioussness. Urinary incontinence
can occur during this attack.
Also get blood pressure monitoring to check fall in blood pressure. If she is on some medication, consult your doctor and disscuss for its continuation.
Also have CT Scan
done to rule out for any other cause.
I hope this is helpful to you.