Yellow Tang (Sick?)

[D-Rod]

I can't get a decent picture. My tang has what looks a piece of crushed coral sand on its bottom fin, however i don't have CC.
It is grey in color and appears to be stuck and he is acting more aggressive towards tank mates and me and also is wiggling his back side alot. Does anyone know what type of fin disease this might be.

Thanks
D-Rod

 

[D-Rod]

It looks like a very small size grey cotton ball (half the size of a BB)

 

[Steven Pro]

It might be Lymphocystis. Try to find some images on the web of that for comparison.