First off, you need to find a different vet. I wouldn't have any confidence in a vet that recommended what your vet did. Feeding all of those starches, especially to a rabbit already having problems with excess cecotropes, can easily cause further digestive upset and GI problems. Not to mention the treatment that was prescribed. Did the vet do an eye stain to check for scratches on the eye? Did the vet check for debris causing the irritation? Was an eye drop prescribed? 2 days on an antibiotic is
not enough if there is a bacterial infection causing the eye irritation. All 2 days on antibiotics will do, is make antibiotic resistant bacteria. If you need to see a vet again, look at these lists to see if there might be a better one near you.
http://rabbit.org/vet-listings/
http://www.rabbitsonline.net/forumdisplay.php?f=21
It is possible for things in a rabbits environment to cause nose and eye irritation. As was mentioned by missycove, they can sometimes be sensitive to things like the ammonia from urine buildup, things that are too dusty, to a particular litter, hay, or even household chemicals or other scented things that are normal to us. If there is no damage to the eye causing the irritation, you could try changing to a different litter, different hay, removing perfume and other scented things in the area around your rabbit, to see if any of that helps.
As for the continued excess cecotropes, did you change your buns diet at all? Did you switch from the alfalfa hay to a grass hay like timothy? The bene bac may help, but it is more likely that you will need to make some changes to his diet. If any of the poop is sticking to his fur, you will need to try and keep him as clean as possible to avoid the possibility of fly strike. If you do go to a new vet, having a fecal sample tested may be a good idea as well.
http://rabbit.org/disorders-of-the-cecum/