Possible Sick Comet?

Hi,

I am a newbie to fishkeeping. I set up a tank about 3 weeks ago. It is a 29 gallon with two goldfish. My comet has been acting fine, but I noticed that he had white poop, and his tail(he is white) looks a little irritated(can see his veins a bit?). He is swimming normally, actively looking for food and he swims with the other fish in the tank(he is not keeping to himself).

Since I am new at this, I do wonder if feeding him too much could cause the white poop? Or is this a bacterial infection?

Water quality seems fine, ammonia did get to .50 but I have been doing 25% water changes to make sure it doesn't spike up. The PH is around 8 but all the water here is and LFS said that it is better to leave it steady then keep adjusting it, that the fish would adapt. Nitrites, Nitrates, are testing 0?

The water has been cloudy, but I was assuming it was bacterial bloom? I have a bio wheel filter.

Just trying to go through any questions you might have asked about the water, fish, etc.

Thanks!

Cecile