Another thing to look at, make sure you have your shower head valve open. If it is closed, & the hot/cold valves in the shower are still open, you will get the same effect as you described. If you have single faucet fixtures, you could also have bad "O" rings in the fixture.
Steve & Sharon
'13 Dodge Citadel (hers)
'12 3500 Dodge Mega Cab 6.7 Cummins (his)
'12 Crossroads Rushmore RF38FL (ours!)
Barry, the ADHD x 2 German Shepherd mix, Granddog.