omg... the Ich is back . What's the deal?!?!? I need help.

[OCDP]

I am having a real hard time here guys... this is upsetting.

Some may know that I had a pair of true percs about 2 months or so ago, they both came down with ich.. and sadly never made it. (This whole time I had a yellow watchman in the tank and is still there) ... so they didn't survive, which was upsetting (already in rough shape when I got them)

So I figured great.. the ich is going to spread to the YWG now... but to my suprise, it didn't.. and we are talking months.. so about 3 weeks ago I put in a bicolor blenny.... no ich, no nothing... on either fish.

I put in a pair of true percs from golds on Tuesday evening, the pair is in such good health and spirits... and then last night I spotted ich on both their bodies!!! WHAT IS THE DEAL!?

How does the ich not get to the yellow watchman goby (who has been in the tank since the last pair of true percs died from ich, and poor health when recieved) .. and how does the bicolor not get it?? and then of course my fav. fish get the ich...

So you know, I am at a loss.. no QT, no supplies for QT, no money for QT ... I thought I had gotten off lucky, I admit to that... but I am just soo confused as to why these two fish didn't get ich, and they have both been in the tank for a while ... and then the clowns are in for one night, and the next I spot the evil white spots..... I am so PO'd !!