Eukanuba Poland
My first suggestion would be to have your vet do a skin scrape to rule out mites.
If mites are the culprit then your course of action will be totally different.
And as stated above without the screening test it will be difficult to pinpoint exactly what he is allergic to, given allergy is the problem.
Allergies can be environmental or food or fleas.
At your dogs young age it will be impossible to tell if it is a seasonal allergy to plant material just yet.
I included a link above, it seems that Eukanuba foods are available in Poland, of course it is in Polish, so I couldn't read it, but there is a contact number.
And they do have some hypoallergenic diets.
Your vet should have other resources for diets.
Since I don't know how things are packaged and labeled in Poland I am a little hesitant to suggest anything over the counter for the itching, I hope you understand.
Edit: I forgot to add that Eukanuba diets may only be available with a prescription from your vet