Allergy or irritation or behavorial habit, can't tell from here by: Barbara
It?s a possibility, sure, but to diagnose an allergy you first need to schedule an appointment with your veterinarian.
Before you go, read about allergy symptoms and write down a list of symptoms your recognize plus estimate the date these started.
Then try to recall whether there have been changes in your dog?s environment or eating habits (take a look at your calender or agenda). Itching and scratching can be the result of chemical irritation. Perhaps you tried a new flee or tick repellent?
Another reason for excessive scratching can be stress or a way to get attention. It then turns out into a behavioral habit.
Gathering this information will help answering some of the questions your vet is likely going to ask you.