Unidentified Yellow Tang disease

[Dubaidogfish]

http://youtu.be/SQSHx0y9SRs
<iframe width="960" height="720" src="//www.youtube.com/embed/SQSHx0y9SRs" frameborder="0" allowfullscreen></iframe>

Hello,
I have a yellow tang with pimples under its skin that form white growths and then develop slowly into a white crater. This Tang has had ich before but that looked completely different. There seem to be a lot of people with the same issue and no body seems to find an answer. Was fine for about a year and very strong fish. I have done very low hypo 1.075 for 2-3months at 29 centigrade and has had no effect, freshwater dips for 20mins, paraguard dips and dosed cupramine in the main tank but nothing seems to fight this. Have had success in curing fish of velvet and ich before but this one is tough. The fish is eating fine but must have about 20 pimples on it now. Ich came and went very quickly in terms of dropping off then coming back the next day but these things seem more permanent on the fish. Suggestions of lympho or black ich not fitting what I see.

Seems same issue as these: http://www.reefcentral.com/forums/showthread.php?t=1336758 and http://www.reefcentral.com/forums/showthread.php?s=&threadid=1568912

Thanks in advance

 

[Dubaidogfish]

So after another freshwater dip there was some bleeding around some of these attachments, particularly under the front left fin and some on other side. The white craters near the dorsal on this side I think are healed scars although the parasite might still be resident at those sites but they are not raised more like mini craters

 

[Dubaidogfish]

Can't seem to edit the post above says is invalid but the picture link is: http://picthost.net/v.php?id=88db951f8f37a96f7db5af99476ba299