IIt is normal for cavaliers' eyes to water a lot and leave discharge on the fur below their eyes. Some don't have this, some have a bit, and many have it quite heavily (like a lot of small, large eyed breeds). Puppies seem to be worse than adults -- I have known breeders to say they believe this is because the skull is still growing and later fits better around the eyes.
The water eyes enables a harmless growth to occur in the damp fur which can have a yeasty smell. This is not an infection, if this is what you are smelling. You can buy specially made eye pads to wipe this area clear (being careful to always avoid the eyeball and wipe away from the direction of the eye). Others simply use water, or contact lens solution -- the type you can also put in the eye (this is important!) that also cleans protein deposits on lenses. Overnight the discharge can get thick and gooey -- all my dogs have this in the morning.
So it really depends on whether what you are seeing is really an indication of an eye infection, or is normal discharge.
Whatever you put in the eye may just have dried up some of the normal discharge and hence looked like an 'improvement' -- but really , 'normal' discharge is normal.
It is determining whether what you are seeing is normal.
I'd go back and talk in more detail to your vet. Or see a different vet and get a second opinion. If she is pawing a lot at her eyes it does suggest some level of discomfort. Usually the vet will do a simple test to check for scratches. Also did the vet examine her for ingrown eyelashes? Some cavaliers have this and the eyelashes brush against the eye, causing pain and eventually possibly blindness if it is not dealt with.
To be honest, from your description your vet didn't seem to really check for a range of problems. I'd take her to a completely different practice and see what they say. You could also go to the vet school there and see an eye specialist.