it is probably the combination of water retention and usage of computer in bad posture.

Try stop using the computer for a week and see if the pain go away. If you cannot afford to stop using computer then make sure you are sitting in the right posture and using the mouse or keyboard with correct angle. Try to use arm/wrist rest. Get a good quality mouse with good grip and keyboard that provides good feel when pressing.

If you do not take car of this, you might end up getting karpal syndrome. But that is only for extreme cases. It can easily be avoided with the suggestions I mentioned above.

It's possible that when wearing the bracelet, it subconsciously caused her hand to bend or not bend in the wrong direction. To know if this is placebo, try getting a normal bracelet but with built material as close to this Phiten as possible. Wear it when problems arises again and you will see. Best is, tell her it's another brand of Phiten but have similar effects so that wearer do not notice the attempt at busting the myth.