sounds like you O.D.. your iodine. how big is your tank and did you use lougohls or tech-I(kent)?
also did you test for iodine before you dosed it??if so what did it come out at??
Unless you have allot of Xenia and i mean allot i wouldnt dose iodine especially if your doing regular water changes..
The first thing i would do would be to do a 25% water change and then leave the tank alone fore atleast a month. that means just change out your filter pads and add top off water . thats it! this is only my opinion but sometime we try to make things better in our tanks when there is nothing wrong to begin with. your tank will tell you if there is something wrong with it and remember ...nothing good happens fast in an aquarium only bad things happen fast.
as far as the leather and pom poms go the damage is already done.
now you just have to wait and see if they will come through it.
be patient im sure things will work out fine and remember the
only remedy for a mistake is time.

Robert