this sounds like a microphonic pickup issue. I have high quality pickups and never have feedback issues on my rig. My friend came over to show me a guitar he picked up and I let him plug his "new" guitar into my system. It fedback uncontrollably.
Years ago, I had a pawn shop guitar and it had the most awesome sounding pickup I've ever had. If I used it in my dormroom, it was no problem. But I was jamming with a friend and during the pauses between songs, if I spoke, you could hear it through my rig! That is an extreme case of microphonic pickups! The diaphram inside a microphone is SUPPOSED to vibrating/wiggle/move when air passes into it. It converts those vibrations into sounds. However, the windings in your pickups are NOT supposed to vibrate. Your pickup is not supposed to move due to air passing by it. It is supposed to convert the electromagnetic energy that is created when steel strings vibrate in a magnetic field (your pickups). So, the guitar strings ARE supposed to vibrate, not the steel pickup windings. If you turn up an amp really loud and you don't mute your guitar strings, they will start to vibrate and cause intentional feedback - an awesome tool for guitarists! However, if you stop your strings from vibrating, and you STILL get feedback - that is a microphonic pickup. You can try to home remedy wax pot them, but if you are on this forum and own a Fractal of any generation, I would suggest you buy a new, better pickup. Stick with seymour duncan or dimarzio and you will never have to worry that you are buying a pickup from them that is microphonic.
Good luck
