There's usually a shutoff button on the shower head itself. Did you make sure that was open? You push it one way to open and the other way to close. (Your indoor shower head should have one, too.)
Allows you to turn off the water while you soap up without having to mess with the faucets and screw up your temperature setting.
1988 Coleman Sequoia - popup (1987-2007)
2012 Roo19 - hybid (2012-2015)
2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10