So today I went to empty the water out of the passenger side floor pan the day after a full day of heavy rain. After I pulled the floor mat out, I went to pull the floor plug and as soon as my finger went into the water, I could feel an electrical current run through my finger. It wasn't extremely strong, but it was enough to cause a little sharp pain. The water was not very deep (maybe half an inch to an inch?). I could also feel the current if I touched the door entry guard with my forearm, but not with my finger (maybe my fingers just aren't sensitive enough?).
This leads me to believe that something is shorting out into the tub somewhere. The only electrical modifications I've made are a new head unit (which is wired in the same fashion as the factory head unit) and a small amp for the sound bar. I did have to drill a small hole in the passenger firewall to get the positive lead through, but i plugged it with a rubber grommet before I ran the wire through, so it should not have worn through. Anybody have this issue before or have any ideas what could cause this?