Have you tried adding some pumpkin to his food? This usually gets my two regular....
Pumpkin can be found in the baking isle, but make sure you use pure pumpkin, not any that is pumpkin pie with added sugar...
We put about 2T on their food...
I personally wouldn't take a chance on having your yard/home/own dog infested with a parasite. And some of them are zoonotic and you can get them yourself. If it's giardia, for example, you have to wear rubber gloves to clean up and spray the area with a bleach solution to kill the cysts, even in winter. I would take a specimen to the vet just to be on the safe side, and gets meds started if needed.
Did you change his diet at all? Also, are his stools more frequent than normal, or is it just that they are "loose"? I think I'd take a stool sample in to the Vet just to be sure it isn't a parasite.
I was thinking that the food change might have caused the loose stools, but I think this has been happening for at least four days, right? I would think it would be starting to improve by now if that was it. Like Karen, I think it's best to rule out parasites. If that's not it, we can go from there.
I fostered Charlie/Marley a few weeks ago. He had loose stools that I thought would get better but didn't. He had hookworms. I treated him (vet) and he was better in 2 days.
I agree, take him to the Vet, but also try a little white rice mixed in his food...it works wonders for Billy. We give him a little every night and it seems to keep his poops perfect