It does sounds like a food issue. If you change foods you have to change everything including treats and the Purina Lamb and Rice has corn, chicken and mixed animal fats as a part of the ingredients so its not really a lamb and rice only food.

You can read here about inflammatory bowel which can be triggered by food allergies

http://www.marvistavet.com/html/body_inflammatory_bowel_disease.html

And foods you might try would be more likely found in a pet supply store (and not always the big box stores) such as diets of Fish and Potato, venison, or rabbit etc. where the protein source is new and there are no grains in the food can work for many dogs for example. Another option is the hypoallergenic diet from your vet Hills ZD. Changing food does no good if you feed the same ingredients. Remember food changes have to include all treats and can take 8-12 weeks or more before you see results.

A lamb food that woudl be only lamb and rice would be California Natural Lamb for example.

Hope this helps you!

There are home cooked recipes but the problem is you want one with no allergens in it which can be hard. You can shop around for a food which may work at a reasonable price.

Wellness Simple Food Dry Dog Food and Natural Balance Dry Dog Food may have recipes that will work as might the California Natural Lamb.

They make dog biscuits too.

Worming using a wormer such as Panacur (fenbendazole) might help too.

But here is a home cooked meal

http://www.globalpaw.com/forum/dog-nutrition-dog-food-forum/48244-homemade-hypoallergenic-diet.html

and there is one on this site as you scroll down to DOG ALLERGY DIET

http://www.lowchensaustralia.com/HEALTH/diet2.htm

and the supplement here can be served as a whole diet just pick a 'new' protein

http://tedeboy.tripod.com/drmichaelwfox/id19.html