When I read your symptoms I think of two more possibilities.
1) fleas - have you applied any flea protection?
2) allergies - My Merry had the same symptoms at a very young age and finally at 2 years old, I took her to a dermatology vet and it turned out that she was allergic to the ingredients in most dog foods and treats. She is allergic to beef, chicken, wheat and corn. Now that I don't feed her these things, her itching stopped.
I am sure if you go to the vet, he'll eliminate a lot of the ideas we are listing and come up with what is bothering Ollie.
Let us know what happens.
Charleen and Cav's: Pippin (ruby male), Merry (b&t female), Luke (blenheim male) & Jolly (tri male puppy)