Our fox terrier cross is constantly scratching and has made her skin red raw. She doesn't have fleas and there's nothing visible. Been to the vet with something similar before and he thought it could be a habit. However, this time it's worse and I want to alleviate her symptoms. Any ideas?

Sounds like a possible allergy. Sadly there's no way to tell you for sure that this is the cause, and even if there was, there's no way to tell you what the allergy is.

I'd go to a specialist.

You could always try and introducing fish oil/omega fatty acids into her diet.

Just like us, dogs can suffer from just plain ol dry skin. The omega fatty acids would help with this problem from the inside out. It takes about 3 weeks before you notice anything and 6 weeks before her itching stops or subsides.

Even if your pet is suffering from low grade allergies, fish oil will help the skin build up some type of barrier defense.

Seeing as how you have a small dog, I wouldn't suggest purchasing human grade fish oil. Sometimes when over dosing fish oil, the dog may become fat. Speak with your vet about purchasing some from them, or look online and purchase the formula based on your dogs weight.