I have a four year old labradoodle and a 10 month old labrador. The doodle has had skin issues since he was a pup. It seems to be seasonal so we suspect it's allergies. I'm sure it doesn't help that the doodle likes rolling in park grass (amongst other things) and covering himself in grass clippings.
I use Advocate once a month for fleas, heartworm etc. I bath him with Maleseb Shampoo probably once every 4 - 6 weeks (approx.). He also gets a fish oil capsule daily. I also use Aloveen instaed of Maleseb when he's not so itchy.
If you suspect allergies, try and monitor food to see if there are any food-triggers. Eggs seem to set off the doodle.
When the itch gets bad, a syringe full of children's Zyrtec in the morning and evening seems to help alleviate symptoms but consult your vet before doing this.
Hope this helps.