Please help! Flashing goldfish

[Absolute2purity]

full grown comet goldfish 10 inches in 75 gallon tank has been flashing and prazi pro hasn't helped after 4 days. Could this be a protozoan infection? internal? hes a white goldfish so i dont see anything on him.

parameters are fine ammonia = 0

fed 3 times daily good diet.

only is flashing about once every hour or 2 maybe less but im very concerned and doing my absolute best to help.

i have ich-x as well but idk if its a protozoan internal parasite.

 

[Autumnsky]

Ich has a life cycle and at times you will not see them attached to the fish as they fall off start the attachment to the fish with new ones as well.

Here are some articles, 1 for identifying illness and a couple about Ich.

https://www.aquariumadvice.com/fish-disease-index-for-diagnosis-and-treatment/

https://www.aquariumadvice.com/ich-ick-white-spot-or-whatever-else-you-call-it/

https://www.aquariumadvice.com/freshwater-ich-yuck/