Honestly I would remove the dead heads as well as the ones that show signs of declining on that same colony. Chances are they are on their way out if you are losing them that quickly...leaving them in the tank may risk that infection spreading to your other colony.
I've seen numerous threads on attempted dips to save infected euphyllia...and it seems like once it shows signs of infection it's best to just frag and remove anything that looks bad. Success rates for treatment seem low, and since research points the finger at vibrio vulnificus bacteria infection being the cause...anything less than an antibiotic that targets gram negative bacteria is unlikely to work.
Ciprofloxacin works well against vibrio and targets gram negative bacteria...and it might be relatively easy to find. Other antibiotics they use for vibrio vulnificus are going to be next to impossible to obtain. If you want to try to save any struggling heads I'd try the cipro as a dip first...but no idea on the dose you would need for an effective dip though. I can tell you that Furan-2 is supposed to be good against gram negative bacteria....I tried it but it did nothing to save a wall hammer that got infected a while back.
Do a nice large water change (20-30%), run some fresh carbon...and keep an eye on your other colonies. If it is brown jelly disease, hopefully you're able to keep it from spreading. I had a little 28g nanocube and only lost one colony (wall hammer), and a single head on a neighboring colony when I dealt with it...so it's not impossible to stop.