As dawg53 recommended, Valbazen is a very good wormer. You can also use Safeguard liquid goat wormer, dose will be higher. Those are the ones I use, you direct dose each bird. You can also use Wazine (I've never used it as I prefer to direct dose), Wazine will only get roundworms, while the other two are more broad spectrum and will take care of most others also. You can search here for dosing info of each one once you decide which one you want to use, there are lots of threads on worming and doses. I can get Safeguard locally, I have to mail order Valbazen. I would suggest that once you worm with whatever product that you use, try to have a fecal float test done in about 6 months to see if you have any recurrence. For some flocks once or twice a year worming is sufficient, for some it may be more, just depends on the worm load in your particular environment. They can pick them up easily in the soil and can be carrying a heavy load before you may see one in droppings, and they will often act fine. Sometimes runny droppings is a symptom.