RV Hot Skin. Mystery solved!

Hi all,
Turns out there were two wires crossed in my garage's fuse box. I've owned this old house for 18 months and the garage is also quite old. I am not an electrician, but my contractor buddy said there were two sets of wires in the fuse box that should have been black to white and black to white. Instead I had black to white and white to black. The 2nd set was the problem. As soon as my buddy switched the second set to black to white, everything was fine. This problem never affected the lights and other interior garage outlets or anything else I plugged into them. However, once i added an exterior outlet for the trailer, the problem surfaced. I still am going to have the fuse box replaced with an updated electrical panel and the outlet for the trailer switched to a proper GFI outlet. I am just so thankful my wife is doing much better and the issue wasn't with the trailer. She initially was refusing to ever use the trailer again, but now is warming (no pun intended) up to the idea of camping again.