If it already has the infection there probably isn't much hope for that head. But, do NOT blow of this jelly into your aquarium water, it WILL affect other LPS corals including your other hammer heads, if that jelly spreads in the water. For some people, it may just affect that one head. Sometimes it occurs when you try to frag them by breaking off a branch and some tissue gets damaged. But for me, almost a year ago my green torch got it and it spread through out my entire tank killing off almost my entire LPS tank in about 3 or 4 days. I am NOT saying this will happen but I'm just sharing my experience. Since then I have totally restarted my tank.
Here are the solution steps I found. Although I wouldn't do a 25% water change, maybe like a 10% or 15%, and then do another one tomorrow or something.
Treatment For Brown Jelly
a) GENTLY Siphon as much as the Jelly Mass as Possible
b) Remove infected coral and treat with an Iodine Solution like Lugols Solution.
c) make sure that your corals have adequate flow. Not laminar, but multi-directional and random
d) Skim, Poly pads, Activated Carbon are recommended
e) 25% water change.
f) check parameters
I found this on this website: It also has information about other coral diseases and treatments.
http://reefshow.com/html/modules.php?name=Content&pa=showpage&pid=60
Kelly