You can tell them to try cutting the worm and examine stool for ova of worms.
Given your histiry of pet having worms… may be that thing u saw was surely a worm…
Worms can't be easily broken by stretching and when you cuctt them you find its body like a tube… that would confirm the worm.
can come normal if not taken seriously…
If you see thread like… its thread worm and if u see noodle lijke; it is like round worm… remember worms don't get broken easily.