Peacock With A Bubble On His Head, Hoth?

[humpy_the_humphead_wrasse]

all stats are optimum, but there was a lil ammonia 0.25 found when i tested the other week so i did a couple of big water changes and ive just looked tonight to find one of my small peacocks has what im pretty sure is a small bubble on its head. is this hoth? im thinking i might re start the anti bacterial med i started the other day

 

[WILDER]

Bybbles can be many things, bacterial to parasite.
Can you describe the bubble in more detail.
Is he to near an airstone.