Secondly, I'd have a luthier check out the bridge on your guitar and see if you can get it filed down and smoothed over. Lot's of times there is a nick or blemish on the surface of these and that will actually cut the string while you are playing. A common mistake for players of ANY instrument is to fail to spend a few minutes warming up prior to serious jamming or gigging. Dear CrazyGlue, Phantom power has nothing to do with the costume I wore last Halloween - and I still don't know how all of those cat parts got in the freezer in my basement. What Phantom Power really relates to is certain types of microphones need external power supplies to make them work.
Many mixing boards have phantom power capabilities to run condenser type mikes.
I guess we know what you are going as this Halloween. I want to get a new guitar because I think this one is broke. There are a couple of reasons for your sound issues. You probably need a feedback reducer that fits in the sound hole of your guitar and will help to eliminate some of the boominess and feedback. Any decent music store will have one.