Weird goldfish trouble and real live worms

Question
BACKGROUND

The tank has been set up for a couple of months.  There was some bouncing around of chemicals, but water changes and additives were attended to every day.

55 gal.

Two goldies, a 4" comet and 1" Shuby.

Undergravel filter plus TWO whisper 40 filters.

ph-7.8 -8

ammonia- 0-.25

nitrite- 0-.5

I have had to make water changes due to cycling.

I was doing 20-25% most every day because I had to keep the nitrites and ammonia in check.

First of all the 1" Shubunkin is perfectly fine.  

4" goldfish had a white bump on his lip that turned into a cut. Then a scratch on the head appeared and a couple roughed up fins.

The scratch on the head turned blackish looking and stayed that way for 5 days.  

2-3 scales went missing and then black spots started taking over the fish.  He was getting blacker by the day.

I removed a decoration that may have been trouble.  When I did there were huge strands of white cloud looking stuff, i assumed to be fungus.  But no white on fish, just black.

8 days Melafix. 4 tablesppons salt in 55 gal, water changes to keep chemicals correct.

put in pimafix for one day and it clouded the tank with bacteria.

Everyone said it was ammonia, but ammonia has been in check and ONE FISH IS FINE, the other bad black spots.

Allexperts said, these are burn marks that will heal in two weeks.

Then I used prazipro.

The fish turned back gold in 4 days.

BUT I WENT TO CHANGE MY FILTER AND BOTH OF THEM ARE FULL OF WORMS THAT ARE BROWN AND ABOUT HALF INCH LONG.  SOME DEAD IN FILTER, SOME ALIVE.

And my tank water is getting green with algae.

Geez.  live worms is scary.  should i use more prazi-pro or something to kill worms or what?

fish are both acting normal.

thanks.
David  

Answer
David,
Something you added to the tank was infected. That's why this is a good idea to have a quarantine tank - so new or sick fish let the problem develop OUTside your main tank.
If you can get another tank and remove only the healthy fish for now, you might keep him stress free and healthy with clean water and salt in that tank until you get your other tank fixed. You can get a ten gallon tank without a hood for about 11 dollars.
I recommend cutting waaaay back on how much you are feeding, and doing some gravel vacuuming. Scoop out with a net any uneaten food immediately, and check filters, gravel and plants for dead fish or decomposing food and remove. If you remove the source of food, the worms should deplete.
You may have to completely throw out your filter, since any chemical you use to remove the worms will kill off your biofilter anyway.
As long as you keep up on the water changes your fish can survive for a little while without filtration. However, if you do larger ones you should see improvement within a few days, as long as you do what I mentioned above as well.
Continue to add BOTH melafix and pimafix, and try to keep those fish alive! I'm rooting for you.