I have fixed this problem before (microphonic tube) but now it really only happens when i use my tubescreamer, english muff'n, or distortion +. The amp is a classic 30 and my guitar is a ibanez rg 370 with super distortion in the bridge a paf pro in the neck.

Can anyone help? Would a noise supressor pedal do the trick?
Are you using a TS and distortion together with your guitar volume maxed out? To much signal equals feedback.