Lab restless and full of gas

Question
Stats:  Black Lab, 80 lbs, consistent weight, excellent health, 8 years, been eating Purina ProPlan since puppy.

Within the last six months he's been passing gas.  What's unusual is he has never had this problem. Ever!  I bought a new bag of food in case the last bag was tainted.  Same symptoms. His stool is regular.  No medicine.  He's an indoor dog so no chance of eating something outside or inside for that matter. It's 1:30 am and he is restless and passing gas at an unusual rate...doesn't want (or need) to go outside.  Any ideas what could be causing this disturbing change to what has been a nearly perfect pet and companion?

Mike  

Answer
He may have developed a food allergy to the ProPlan food.  First thing to try is adding 3 tablespoons of PLAIN YOGURT to his food twice a day to see if that helps.  If not, I would recommend getting another food that is free of corn and soy....preferably all natural so it is easier to digest.  A few brands to look into are Nutro Natural, Prairie www.naturesvariety.com, Wellness, Verus, Eagle Pack, Flint River Ranch, Innova, California Natural...