I feed a Prey Model Raw diet which is very good for allergies and problems like you are experiencing. I know your vet probably recommended Science diet but it is not one of the better kibble foods. I would at least change to a better food and really consider a raw diet. Here are some links with addl info to get you started in case you're interested:
The Many Myths of Raw Feeding RawChat : Raw Chat rawfeeding : Raw Feeding for dogs and cats!