In those pics,I didn't see any brown jelly on your coral.Thats no to say,that yours didn't have it.If its brown and stringy mucuus then thats something completely different.Corals regulated the zooxantellae population in there tissue by expelling it out through their "mouth".
There has been no known causative pathogen yet identified that causes Brown Jelly condition.With that,the only treatment that has worked for me,is blasting the jelly off.If you have a water dental pic,that is great as the high pressure really gets it off.Then doing Lugols dips.