Lee reminded me of something about fecal samples - err, poop tests. The poop needs to be x hours old or fresher. If you might go that route, call the vet you'll use and ask them how fresh does the poop need to be in order to get a solid test result. Either way you go, best find a good vet now, even if you don't use it. When you really need it, or you decide you gotta take him now, that's too late to be picking a vet. A vet visit would likely cost between $50-120, depending if its emergency or what the local rate is.