My sick tang

[Constantin]

please look at these pictures and tell me what this is, initially i thought it was ick, but now i suspect brook...
The tang is active and eating, but is skinny, been skinny since i got it.
however, it now developed 2 bulges in the abdomen, also, the front of the tang head is noticeably lighter than the area behind the eyes.
I have a small hippo tang that also has some bulges in the abdomen, both eating like pigs though.

please help me out

 

[RyanSweatt2004]

looks like it could be hole in the head or lateral line erosion, both are possible signs of poor water quality and can take a long time to heal once good water quality is achieved.

 

[Sisterlimonpot]

Please post your water parameters.