Lesion on clownfish?? Please help diagnose!

[spiffyreefer]

Yesterday I noticed my black ice clownfish had some sort of lesion on his head. In blue light it looks gray and in white light it looks pinkish. Based on my research, it looks like it could be some kind of bacterial infection, but I could be totally incorrect. It's hard to say because he is mostly white, but I do not see any other spots or anything on the rest of his body. I've had him for nearly two months and he seems okay otherwise (not breathing fast, swimming, eating). It is possible that he may have actually had this for a while, I recall noticing a faint grayish spot before, but at the time could not tell if it was problematic. The other clownfish and watchman goby in the tank appear totally normally. The only thing that has changed in the tank recently is that I added two trochus snails from a LFS (about 3 weeks ago). I attached a few photos (sorry for poor quality) that show the spot on his head.

Any thoughts on a diagnosis and how to treat??

 

[Big G]

Sorry can't see much from the pictures. A closer up pic would be helpful.
White/white-ish grey, redness and or necrosis can indeed be an indicator of a bacterial infection. Important to note that bacterial infections are usually a secondary actor. Something else has caused the infection: injury, illness, parasites.
Has the fish been treated with anything prior?