Does my clown have itch or ???

I'm worried that my clown might have ich....

I first noticed this white spot yesterday. It looks more like some sort of detrius stuck to his fin rather than the "salt encrustation" look that people say is itch. It's not flat with the fin, but rounded like the head of a pin. His appetite is normal and so is his activity.

Any ideas on whether it is or not? I thought the attached pics might help, red circle area is fin in question.

If it is itch, what should I do? He's in the main reef tank with corals and inverts. Unfortunately, I have a Royal Gramma in my spare 5g tank right now, so I can't move him there either which leaves me wondering what to do to quarantine him if it's itch?

its ich not itch and i dont think it is becuase its only on one fin, maybe fin rot?