Not eating, difficulty in respiration can certainly be signs of a parasite.
Velvet generally starts in the gills before becoming visable as tiny round white dots and usually kills the fish in hours if not a day via suffocation. Ick provides more time but is just as deadly as well if untreated, appears as white dots as well, but not perfectly round.
I can't see anything visable in the pic, but the fact of two physical changes certainly creates suspect.
Only CP or copper can treat both velvet or Ick at the same time. IMO, no general cures do much. Hypo and TTM only work on Ick. I would likely start to treat now, clowns are quite Hardy and usually respond well to CP. if you do treat, always "try" to feed foods high in protein twice a day, but vacuum up food not eaten....provide a place to hide.....keep light real low...
Lower salinity to 1.017-1.020, will help him breath easier, careful watch on ammonia Ina QT.