Fish parasite?

Question
We have clown fish, parrot fish, bala and red tail shark in our 90 gallon tank.  
They are large as we have had them for more than 10 years.  Until recently we
had someone who took care of our tank but he is now gone.  One week ago
the parrot fish started laying sideways on the bottom of the tank.  They stay
there until it is feeding time.  All of the fish seem itchy and they shake there
fins.  As well the parrot fish have become aggressive with each other and they
never were before.  The Bala shark is covered in what looks like bubbles and
his eyes have clouded over.  The clown fish keep going to the top of the tank
and they never did that before.  The local fish store told checked my water
and said there was no amonia and the nitrates were a little high.  They gave
my a product called prime and also Noxich Ick Will Stop remover.  I have
added both to the tank.  They said to do 35% water change evey second day
and we have done that twice now with no improvement.  Please help.  We love
our fish and it is really sad to seem them distressed.  

Answer
Dear Nicole
i know how you feel nicole first off i would try and get hold of this guy who took care off your fish and ask him if he did everything correct. if the parrot fish are getting life threating aggressive i would remove 1 from the tank, and i would put your bala shark in a hospital tank (a hospital tank should have no substrate or live plants but your can but in a ornament for shelter) because it sounds like it has a Disease, the clown fish could be going to the top of the water because the water may not have enough oxygen in it i would completly take out all the water and put new water in (make sure the new water is healthy and clean by putting in water conditioner) and put the fish fish in different hospital tanks i really hope that this has helped you and i really hope your fish survive because they are beautiful creatures

JOEL