Hi 46jeep,
Welcome to the Heartland Owners Forum and Family. You will find lots of great people here with lots of information.
To start with, you need to check 2 things. If you have an outside shower, make sure the hot and cold valves are turned off. Then check the water heater bypass valves are correct, the in and out open and the center bypass closed. Either one of these could cause your problem.
I'm sure some others will jump in also if this does not help.
Jim M