Dog keeps scooting after vet said anal glands are fine

So my 4 year old beagle mix has been scooting across the carpet for about a week now. Took her to the vet, they expressed her anal glands but said they werent that full and everything looked normal.

Shes still doing it though! Multiple times a day. Vet said to just monitor but im getting worried. Has anyone else had this happen? Could it be allergies or something else?

Already switched to a higher fiber food like they suggested. No improvement yet.