diease or wound?

[alanh]

I'm a newby. I've had this fish only tank for about four months. I have four damsels and recently added a tomato clown (musch bigger). After adding the clown, my striped damsel soon started to get what I thought at the time were bite wounds, but today one of the "wounds" is protruding (see attached picture). Is this a parasite? He is acting normal. On his other side he is missing some scales. The other dominos each appear to have a scale or two missing too, but the clown looks fine. Any ideas?
Thanks in advance.
Alan

 

[alanh]

There is only one fish that has the lesion. He has a maybe 10 scales missing or disturbed. Two of the other damsels have a scale or two missing, and the clown looks fine. The striped damsel (in the photo) did appear dominate the tank before the clown was added.
I have had a hard time finding pictures of what any diseases besides ich look like on the internet and in books. arrgh.
All my water tests are fine.
Alan