Help! MY FISH ARE DYING RIGHT NOW!

Around 3 days ago, one of my weather (dojo) loaches began to die. I was going to take it out and dispose of it, but it was still alive. Last night, i think it finally died so today i was planning to take it out and dispose it.

But i was horrified to see my 2 sarasa comet goldfish with a white wispy film covering them, even their eyes. they look almost dead. My other weather loach seems to be dying too, covered in the same thing. Did it have something to do with the decomposing weather loach that was already dead for 24 hours? Last night i fed the fish and loach, everything looked perfectly normal. How could it get this bad overnight? If you want pictures, i would take them, im really disappointed by this sight. it looks like ich, but i don't think it is. WHAT IS IT AND HOW CAN I CURE THEM??? Is there a medicine i can buy at the Pet store? im willing to run outside to go get it.

If it helps, its a 20 gallon planted tank.

thanks

Edit: Pictures of my poor goldfish and loach, can you tell what is it thats killing them?

http://img.photobucket.com/albums/v216/icecubez189/PICT2495.jpg
http://img.photobucket.com/albums/v216/icecubez189/PICT2494.jpg
http://img.photobucket.com/albums/v216/icecubez189/PICT2493.jpg
http://img.photobucket.com/albums/v216/icecubez189/PICT2490.jpg

heres two new pictures, i can see the white film on them but it doesn't show up too well on picture because of flash probably. fish keeps moving around too.

http://img.photobucket.com/albums/v216/icecubez189/PICT2498.jpg
http://img.photobucket.com/albums/v216/icecubez189/PICT2499.jpg

Velvet sounds like it but its not a yellow colored film, and the skin doesn't look likes its peeking off.

Although i would like to believe that its Ich, they are not small white dots. The fish are not scratching on the rock or gravel. They are floating in the water and floating up sometimes. The breathing doesn't look labored but i could be wrong at this point. Could it have something to do with the dead loach i had in the tank for 24 hours? or is what killed my loach is killing everyone else?

unfortunately, i do not have my test kit on me, as i would really like to know right now. I just did a water change 4 days ago, i've had these fish since January. Water change happen once a week, sometimes twice a week since goldfish are big polluters, even more so in a small 20G tank.

I agree and know the tank is way too small, i've been trying to find a friend who has a goldfish pond or a much larger tank. it looks like i won't have to anymore if i can't cure them right now :sad: