I did see some small dogs at both Hesperia shelter and Apple Valley shelter. Your chihuahua might be there. Or at Victorville Rescue. I've not gone there yet.
Make sure to go into the shelters and look and let them know.. Pets can lose collars while out. Consider chipping your pets, it really helps getting them back. Very sorry and I hope you find your fur baby.
Thanks! Your answer is awaiting moderation.