Egray8:
Sounds like the main drain to the trailer is blocked...or the storage tank you connect to is full.
Check the storage tank via access cover if possible, or talk with others in the mobile home park (if not on your property) and see if they can help you to determine if the tank is full....if so, it will need to be emptied...
Otherwise, you will need to locate a
main drain cleanout and then rent an
electric cable machine from a local rental store and snake the drain to unclog the pipe. Be sure to get some leather gloves and goggles if you attempt this yourself.
Let us know if you have questions...
MARK