Puppy has dead worms in feces?

We've had our puppy for about 3 weeks (he's about14 weeks old now), and he's been a bit of a troublemaker :) First he picked up coccidia and an internal bacteria, and now I worry we have some more problems. He's had 2 fecal tests (the last one about a week and a half ago) and has never been positive for roundworm eggs but we just gave him a dewormer and noticed him pooping out dead ones (at least in all my research that's what they appear to be)! He was also dewormed twice by the breeder, the last time about a week before we picked him up, and started taking heartguard plus the first week we had him (June 13). Is it possible that these could just be lingering adults that died in his intestines during his deworming (he was sick immediately upon picking him up, so maybe he was unable to pass them) and are just now passing through, or is it possible that he passed to fecal floats while still carrying the roundworm parasite (which I believe is pretty unlikely). I'm driving my wife crazy with all my worrying and I'm taking a sample in to the vet tomorrow to be sure, but if anyone has any experiences that could bring piece of mind so I can sleep tonight, that would be awesome! Thank You!