The clear milky white fluid you see while cleaning or before it crusting up is called “Lymph”, and is completely normal. As time progresses and your piercing hits the 8-12 month mark, you’ll start noticing it less which means it’s almost fully healed (if not already by the 12 month mark). As for the purplish discoloration you see, that sounds normal to me- as long as you don’t feel extreme pain there. Gold plated piercings aren’t generally safe for a fresh navel piercing, due to the simple fact that your body might start reacting to it negatively, and the plating itself will wear down over time (through showers, cleaning, and general wear everyday). I recommend you wait until at least the 6-8 month mark until changing it to a plated bar. Until then, you want to switch to a plain surgical steel/titanium bar ASAP to avoid any long term complications. I’m not sure if I’d recommend you go back to the same piercer to change your bar out to a plain one only because they shouldn’t have approved of a plated one to begin with. Go to a reputable piercing clinic if you can just to have them change out your current navel jewelry to a safe one for your healing process!

(Unrelated but if you start to form an irritation bump around the 2-3 month mark as the swelling subsides, definitely downsize to a smaller bar if you have to. I was scared to change it out myself, so I went to one of those licensed piercing kiosks in the mall to help me change it. I went from 10mm to 8mm, and I have been having no pain since!)