Puppy and food types/teething

Hi I have a toy Cavoodle puppy, around 5 months old and 3.5kg currently. He eats the Royal Canin puppy dry food, as this was the one he had with the breeder too, and up until he started teething/growing adult teeth around a month ago he was loving it!

The last week or so he really hasn’t been eating much, and when he does he tends to rub his face on the couch/floor afterwards (seems like itching?) – is this a normal thing with teething or an indication of an allergy perhaps?

Any insight or advice would be much appreciated!!