It's been suggested previously to make sure the winterizing bypass is closed and the outside shower valves are both closed. Also, if your shower wand has a positive cut off, make sure that the shower valves themselves are both closed.
Also, some water heaters have a mixing valve. The idea is that the water is heated to a higher than normal temperature (which effectively gives you more hot water); when there is demand for hot water, the valve mixes some cold water into the hot water supplied to make the temperature safe. If that valve is messed up, you could get water temperatures that are odd.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch