7 Month Pug Puppy off and on loose stools for over a month-Help please

Hi Everyone, In March my husband and I adopted our 2nd pug. His name is Sayid and he was 4 months old when we picked him up. They had been feeding him puppy chow we slowly changed him to blue buffalo wilderness puppy. He has been doing great until the last weekend in June when he got diarrhea thought maybe he ate something outside which he tends to do. feed him chicken and rice for a few days he was all better then it came back about two days later took him to the vet nothing was found they gave him meds he was all better for a week then it came back. I have taken him to the vet now 3 times in the last month and no parasites or anything sickness related to I am starting to think its his food. Should I switch him to somthing more sensitive? Right now the Vet has me giving him adult formula blue buffalo (what our older pug eats) mixed with rice and it has not stopped. Any tips or food recommendations would be helpful. Also want to mention he is still active and not acting sick at all just super loose stools or diarrhea off and on.

How much are you feeding? Sometimes loose stools are caused by overfeeding...
To firm up the poops, try adding a tbsp of pure pumpkin puree (not pumpkin pie filling) to each meal

It maybe the protein source in the food as well. Switch his protein with the same brand and see if it helps.

He gets a cup a day 1/2 in the morning 1/2 for diner. I have eliminated all his snacks until we get this problem fixed. He currently weighs 13 pounds.

You might want to run him to the vet with a stool sample.

We have taken him 3 times, checked his stool all 3 nothing.

Here is a cute picture of me and him[IMG]http://i39.tinypic.com/207qet2.jpg[/IMG]

Can you check what type of fecal test they did? Most clinics run a simple "fecal floatation" test which often misses parasites. The better test is the "fecal centrifugation" test where they take a larger sample - requires a grape-sized piece, not just a fecal loop, and spin it in a centrifuge. Make sure that test includes a Giardia ELISA test run with the fecal centrifugation test. This is the most accurate fecal test, but the cost should be $50 or less.
Once you've ruled out parasites, he might be allergic to his food. He could be allergic to the chicken, the rice, anything in the food. The food you switch him to should not include ANY of the ingredients of his old food. Unfortunately, nowadays most dog foods include rice, oatmeal, barley, and many different fruits and veggies, so it is hard to find foods which exclude these ingredients. It is good you are excluding treats from his diet at this time.
Lastly, you could try adding a probiotic to his food - either good-quality probiotic capsules, or a spoonful of low-fat unsweetened plain yogurt on top of his food. My dogs get this a few times a week, and they LOVE the taste (strange cause it is quite sour!). There is a rare chance he might be allergic to dairy, though, but I find for my dogs it helps firm up their poop tremendously.

I second adding a probiotic! Scootaloo's gut flora was demolished by antibiotics to fight an infection and she hard horrible pudding poop. I started adding a probiotic and Firm Up to her food and it cleared up after a week.

Thank you the last fecal test that was done they did tell me no Giardia found, I had specifically told them to make sure to run it for everything. I will try the probiotic for a bit and see if that helps. If not I will have to start trying new bland foods for him. It just makes no sense that we would be great for 3 months on his food and then develop an allergy. Thanks for your help everyone.