Welcome to the forum!
Do the doogers have access to the yard and if so have you checked all around to see what might be falling?
I hate to ask this....
but can you describe the poopy object?
(colour size etc.) Is it just 1 object per poo or multiple objects?
fecal test - good idea Winston - if it really is some kind of foreign object like a nut, I'm guessing the techs can see that. If it's a worm or parasite - they'll surely see that as well.