felinefuture, vets also have to recommend commercial pet foods because oftentimes a large company such as IAMS or Purina will sponsor that specific clinic, so they "have" to recommend that brand of food to all their patients, eventhough that particular line of food may not be "good quality" food!

Anyway it can be one of two things as mentioned above -- worms, or anal glands.

If its worms, you need to check your pup's stools. If applicable, pick it up in a plastic baggie, zip it up tight, and "mush" the poo to look for white worms. Nasty I know but sometimes it saves a trip to the vet office.. If its worms then you can pick up some dewormer at your local pet shop, its relatively inexpensive to buy, I do believe even Walmart carries some, though I don't know how good it is.

If its the anal glands, unless you are an expert in knowing how to do it yourself, bring your pup in to the vet to have it done. You CAN do it yourself, but if you are a novice then I do not recommend doing it by yourself without supervision.