Kelly, unfortunately you do not say how long after he fingered her it happened? Does she have any unusual smells or discharge from her vagina?
Did she bleed after being fingered? Could he have caused micro tears in her vagina?
itchiness can be a sign that she might have gotten a yeast infection. This can happen if his hand were not clean or he moved his fingers from touching or inside her anus to her vagina without washing his hands (a BIG NO-NO).
It is certainly possible that she had a bad reaction to his hand sanitizer. He should always end with rinsing in clean water.
If it does not go away, she should see her doctor.
Take care!