Whew! Now I get it. Yes, definitely a window leak, thank goodness. Did you use butyl tape? And did you fully remove all of the old caulking?
Fixing a window takes two people, but it is not rocket science. You can do it yourself, or you can also have a window repair outfit take care of it for you.
I had an identical leak on my old T-139, a 2003 model. I unscrewed the window, removed it, cleaned it all up, installed butyl tape, and re-installed the window. The leak was fixed.
Then, on my newer X-139, we were parked in an RV park in 110 degree heat, and they turned on the sprinklers, which splashed my window with very cold water. The window cracked due to thermal shock.
Instead of doing it myself this time, we took the trailer to a pro. It was not a cheap repair, but it saved me a lot of labor at a time when I was very busy. (Now I am retired and would do it myself!)
2012 Fun Finder X-139 "Boondock Style" (axle-flipped and extra insulation)
2013 Toyota Tacoma Off-Road (semi-beefy tires and components)