Originally Posted by inspectorD
Do you have well water or town water?
Sounds like a valve problem before your tub faucets. I would start in the basement and trace your pipes. Look for a valve with lots of gunk on it, starting at the water heater, could be the culprit.
You can start opening and closing valves, but be prepared for them to leak if they are the old gate style valves. The packings wear out on these.
Unless some one has been messing with the valves This wouldn't be the case unless the valves were closed then you tryed to open them the lines are pressurized if the packing nut starts to leak you can tighten then back up clockwise with channel locks
This really sounds like the shower body going.