FAD, Flea Allergy Dermatitis, is the most common skin problem in dogs. Typically the most affected region is the base of the tail and along the back line. Even if you are not seeing many fleas, if an animal is sensitised to fleas, then it only takes one for the allergy to flare up. There are other causes of itchy skin in dogs including infection (bacteria, yeast), other parasites, food allergy and atopy. You should get to a vet so they can start investigating the cause and give your animal some relief.
Defidentally go see the vet. Or call the pet hotline if you would rather
Could be an allergy or a hot spot. Bathe the area with selson blue and make sure there are no fleas. If it keeps up, see the vet.