Plumbing and Piping - Where'd the hot water go?

We seem to have lost most of the hot water in one of our upstairs bathrooms. On full hot, both sinks (new faucets) and shower (old origional fixtures single rotating control with shower head and bottom faucet) do not provide nice hot water like they used to. Water in the other bathroom upstairs as well as water downstairs gets nice and hot.
When my husband drained the hot water heater recently to clean it and replace the heating elements, he had to shut off water to the house not just the heater itself. He thought at the time that was weird and maybe the value for the shower was messed up letting water drain back into the tank. I don't know if that could be related. Our house is about 16 years old.

I appreciate any advice.

Thanks,
MB

Well, the same heater feeds all the fixtures in the house, so the only explanation for your problem is that the valves themselves have some type of stoppage from the heater... I suspect your diptube on your heater has deteriorated and gotten into the closest valves or the ones that are easiest to get to anway... Turn the water off again, take the shower stem out and check it for trash... while the water is off, check the shut off valves under the two new faucets also... by taking out the stems if necessary... if you don't see white debris in them, then take the stems out of the faucets themselves, and make sure they are clear of debris... Also, how old is the water heater? Is it original to the house? If so, it likely needs to be replaced anyway, instead of changing the diptube...

The hot water heater is about 7 years old. I would not be surprised if muck has clogged up the pipes since we live in limestone country. We do have a water softner but the previous owners didn't. My husband sucked out an enormous amount of junk when he changed the elements (along with four previously spent elements). We'll take a look at the stems. Thank you so much.
MB