Without a microscope you wouldn't be able to tell, unless another one dies/ starts acting the same way might be a tell tail sign of flukes.
Right now you need to keep your water in excellent condition.
Gravel/substrate cleaning and 25% pwc every week. More if you have poor water test.
Help the rest to get as healthy as possible.
I always clean the filter when needed but not at the same time as in the week when I would do the big cleaning inside of the tank, so alternate that, and don't clean the filter in tap water, only tank or conditioned water to save BB.