Pimples on goldfish

Hi guys,

First 3 pics are of yesterday and last 3 are today.

This is my lion head ranchu Brian.

He has some white spots on him and he lives with 2 weather loaches and 2 other goldies in a 40 gallon.

I feel that I need to do water changes more often but I’m too tired and busy so I do it once every 2 weeks, 20 percent.

Strong yet gigantic internal filter, planning to switch to external, any ideas?

So , what could be wrong with Brian?

I can’t add salt you see because of the loaches. So is a Salt bath the way forward?

Any advice pls comment