Welcome to the forum! I'm sorry to hear that your little pup is having some poop issues. Good call on taking a stool sample into the vet - that would be my first thought too. Pups can pick up all sorts of parasites and whatnot, so hopefully you'll get the results to that soon.
Switching to a better food would definitely be a good idea. When my pups were young, they also had problems with loose stools intermittenly. I tried about 3 or 4 different foods before I found one that worked. Eventually I learned that a completely grain free diet works best for my dogs. That includes food and treats (which I make myself - cheaper, and no preservatives). THe brand I ended up with was Orijen, which several people on this board recommend as well.
If switching food is your next step, be sure to do it very slowly - like over the course of 3-4 weeks. Therefore, it'll end up taking probably 6 weeks at least before he's fully used to it and you know if it's going to help.
For days when the stool seems really loose, I would suggest keeping a can of pure pumpkin (not the pie filling) on hand, that you can mix in with his food for some extra fibre.
If he seems to have adjusted well to his crate, than I doubt that's the problem.
If he's gulping up his food to fast, he may be inhalling extra air, which is bound to give him some gas, and maybe an upset stomach.
For an immediate way to slow him down, many people have found it successful to put a kong (or tennis ball or somthing) in the middle of his bowl. That way he has to eat around it and it slows him down.
But if he's a bit of bugger like my two were (are
) then I would just have to watch them closely as they ate. 3 or 4 times throughout their meal, I would make them stop and sit for a moment, and then they could continue. It was a long process, but eventually I had to do it less and less, and now, they don't eat too fast at all.
Best of luck with your little one. I hope you find a solution for him soon.
P.S. Any pics that you'd like to share
We loooooove puppy pics!