110 volt electrical problems

i have a 2006 24' Gulf Stream King Sport trailer and this week have had an electrical problem that showed up out of the blue. i had my trailer plugged into the house like normal to get the fridge cold and when i checked the fridge the next day it wasn't running of power and was trying to run off of the propane. i noticed that the breaker in the house was tripped where the trailer was plugged into. same plug i have always plugged into. i checked the breaker in the trailer and a 15a breaker was tripped as well. after some narrowing down, i found it seems to the be the breaker that controls the receptacles that are not GFI. there is a seperate GFI breaker that controls all GFI receptacles that is working fine. i have turned off all breakers in the trailer, turned the breaker on in the house and one at a time turned on the breakers in the trailer. everything was good until i got to the receptacle breaker then it would trip in the trailer and in the house. the reason the fridge wasnt running on power was because it is plugged into a receptacle. does anyone have any suggestions on what i should check first? wasnt such a big deal this weekend because the fridge runs fine off of propane, but kind of a pain in the butt not having the plugs. and i did try plugging the fridge into and extension cord and into the house and it ran fine. any help would be great.