You can use Panacur, active ingredient is fenbendazole which is the same ingredient in Safeguard.
https://poultrykeeper.com/poultry-medication/panacur-used-for-worming/
Getting a fecal is a good idea. What @KikisGirls said is possible, that the worm was expelled due to worming. Another possibility is that they were not totally cleaned of worms the first time. With roundworms usually two treatments are done about 10 days apart, when using a direct dose...