@tanza:
It should be fresh, you can use a baggie or take a spoon and put some (they only need a small amount) is a plastic container. OR you can stop by your Vet and ask for a container for a stool sample.
I would not try "home" treatments until he is seen by a Vet. Maybe you can get his appointment moved up
+1 to this!
Since it is recurring, he needs to be seen by a vet. It could be giardia, it could be worms, it could be the carrots, it could be lots of things…I would worry about "squirting" diarrhea and dehydration - especially at his age. Please take him to the vet and worry about the home remedies (probiotics, etc) after the vet has given an ok.
I know that canned pumpkin/yams/etc. don't agree with one of my b-kids and actually made diarrhea worse. There are probiotics you can buy in a pet store - Solid Gold SeaMeal comes to mind...whole yogurt also - but with a puppy I would be careful how much of anything I give and would get the vet opinion first.
Oh, and carrots I only give as a treat since they are high in sugar - so I limit those.