To be sure it is worms I would have a fecal float test done by a vet. The wormer I would recommend to start with is Wazine using 1 oz per gallon of water.
Hi We use the product call Vi-tal and it got vitamins Electrolyte and mineral supplements in it on the pkg say 1/4 tsp / 1gal and 11/4tsp / 5gal and 21/2 tsp / 10gal If that helps we got this at family farm and home in wayland michigan. It a feed store. If that helps
I called the co. about small mixtures. They told me 1/4 tsp per gallon of water. After 1st day my chicks got runny tar looking poop. I cut the mixture i had 50/50 with water(diluting it to half strength) and they seemed to do better. Like most will tell you here just watch the chicks and see how things effect them. Good Luck