My dog had something similar recently and he was put on antihistamines up to three times aday he is a westie so similar size. Most dogs for pets are human, when my dog gets tummy ache he has 2.5ml of children's calpol the vet said it is very good for tummy ache in dogs, they can also have paracetamol under the supervision of vet regards weight etc but not aspirin, where as with cats it is totally different.
He also never has treats....and just has burns sensitive dry food, I tried him on raw but he was not impressed.
Also regards the paw a long acting for a week steroid injection breaks the itch scratch cycle.