hi
the first thing i would do would be loking for problem plants in your garden like wandering dew
you might also want to look closely at your pups diet......i found with my staffys science diet would trigger alot of my girls itching but every dog is different. you may want to try a raw diet, chicken wings are good.
there is also a good shampoo called malaseb which i find relives itchy skin
the best thing i did was used the process of illimination two things that really set my girl scratching is beef products and supercoat dry food
my advice.......try and try and try again
good luck