Trailer lights fuse

[Fergie]

Let truck warm up in shed with lights on for about 15 minutes, pulled out of shed made a slight turn lights dimmed came back to full power and then blew. Put new fuse in and it made it a mile and blew. Threw hazards on and decided to go the 6 miles of country roads to a town where I figured I'd sit till light out. Pit fuse in on main Street drove 5 blocks to the gas station and they stayed on while going to get coffee. Starting to get light out so I left figuring I'd cut threw the country. They stayed on for 15 miles then blew. It was light enough where I could keep going. Sitting in line now and doing some digging. It's not just trailer lights going out. It's taking all clearance lights except for the roof lights. Never noticed before cause I never checked them I only looked up at the cab lights. I guess a blond moment. Right now I unplugged the trailer and got lights on. Been on for about 15 minutes and hasn't blown yet. Going to pick up a new relay to try. I have a bad feeling this could be hard to find.