I agree with Pat. The only treatment for capillaria I know of is levamisole or fenbendazole. Fenben can be adminstered in food and Panacure can be administered in water. People also tend to rave about Ksuri, although I've never had any experience with it.
Have you had a chance to examine the feces under a microscope or is it not eating? I would examine any feces because if one is affected, they all may but just not showing signs.
https://www.vetark.co.uk/pages/Worms...spx?pageid=367
https://www.sciencedirect.com/topics...ogy/capillaria