Hi Andrea,
Here is an article on persistent licking http://www.journalvetbehavior.com/article/S1558-7878(11)00122-5/fulltext?mobileUi=0
From that article it looks like the licking is a non specific GI sign. I’m pretty sure I read the full text of that article at one time and the treatment trialed was a veterinary prescription low fat limited ingredient diet along with an antacid.
Doing a well done food trial as one would do to rule out food “allergy” is something you might want to discuss with your vet.
