sudden illness and infestation

Question
QUESTION: 2 days ago I awoke to one of my gold fish having what looked to be huge patches of discoloration and missing scales all over his body. The spots were round and the outer part was a gray color but the inside of the patch was pink like raw skin. This appeared very suddenly and I didn't know what else to do so I destroyed the fish.
This morning however I turned on my tank light and there are hundreds of these little tiny white things crawling all over the glass at the top of my tank that look like worms. I don't know what they are or how they got in my tank. I have googled every parasite and worm and freshwater disease I can find but I cannot find anything that looks like these little worms. Everything I am reading says they are supposed to be brown or red but mine are not.
I don't understand how this can happen all of the sudden. We have not added anything but water to our tank and we do water changes regularly and clean everything like we are supposed to. Please help.

ANSWER: It definetely is a parasite and you are best to treat the tank with something that treats all parasitic problems (if there are fish left in there) or empty the entire tank and santize it completely if no fish remain in there. Kill those parasitic suckers!

---------- FOLLOW-UP ----------

QUESTION: There are so many things on the market that claim to work but don't. Any suggestions as to what I should use to kill everything? (with the exception of my fishies of course)

Answer
I would go with the brand maracyn. I haven'ts had to treat many diseases but maracyn has been what I turnend to when there was a disease. If it doesn't work I can give you something a little more aggressive to try but I can't guaruntee your fish will survive it.

I'm sorry about the delay. I was unable to access the internet