Clown fish sick????

[Vince272992]

Hi I have a one year old ORA clown and today I've been noticing that he is acting wired by hiding for 5min at a time behind my overflow where he usually sleeps so when he comes out I looked at Him really close and u saw on his first white stripe close to the gills that he has a small smudge on the stripe that is a very light pink, he also has a big stomic and idk if he ate something or if this could be something internally as well, please help
THANKS

also 2 days ago I did a water change and all parameters are great