You need to isolate the source of the smell. If it's from the mouth and they're teething then it could be that, but don't miss hte possibility of lip fold dermatitis which is very common in Cockers. Nnothing usually to worry about and not normally something that pupppies get - but just be sure what it is.
As for the ears, if they have a habit of dragging their ears on the floor or in their food or anything else then they will get smelly and dirty
. Simple solution is to just wash the ears. I get a jug full of warm water with some diluted shampoo in and dip the ears in. Give them a good scrunch and then use another jug with clear water to rinse - result non smelly ears. It is amazing how disgusting their ears can get if you let them;)