Illness/Sickness: Abnormal gill, black "mole"

[TheOmegaPixel]

hey,
I recently bought a new golden axolotl, less than a month ago.
The whole time I have had him he has had no frills on his left set of gills and also has had a very small black pigmentation develop on top of it. (it isn't very dominant, and appears "under" a layer of skin.
Underneath the middle gill however a black "mole" is present, the middle gill's tip is also hooked.
The shop I bought him from kept him in a small tank with two other much larger females who recently laid eggs.
Is he Ok, am I just paranoid?
thanks.
(sorry the pictures are bad)

 

[TheOmegaPixel]

Just an update.
He is eating fine but since posting he has began to loose the feathery bits on the other side now.
They have now decreased substantially.
He is also floating more often at the top of the tank.
He tends to come to the surface and suck in air.
He eats a lot.
I ran out of ammonia and nitrate test kits.
And changed his waters week ago.

 

[Kaysie]

You need to get a liquid reagent test kit.

Your tank is likely cycling, causing poor water quality. You should be doing ~20% water changes twice a week, or as needed based on your test kit.

What kind of filter do you have?

 

[TheOmegaPixel]

Yeah I ran out last week of the test kits.
I will get one tomorrow and see.

My filter is an "aqua one" 75L one in a 75l tank.
It has a spray bar that I use to add air to the water
His PH is normal and I do water changes as you stated.
I forgot to add that I use town water and use a water conditioner, I have tank water available but I used it for my fish in another tank and found it went bad within 5 days. (large algae build ups, really bad smells, etc)