Our water pressure in our one shower has just started acting up in the past couple days and I was hoping for some ideas before calling a plumber.

When you turn on the shower, the water pressure is very low whether you're using hot or cold water. If you turn off the water and turn it back on, sometimes it gets decent enough to at least use again, and other times it just stays low.

With the shower water on and the pressure low, if I turn on the water on the sink right next to the shower, the sink's pressure is as good as it always has been.

I'm thinking this is may be a water pressure regulator in the shower head becoming loose, but I have no idea if that is even possible. Any thoughts?

TIA

It sounds like you valve in the shower knob isn't opening properly, or you could have a clog in the pipe calcium etc first change the fixture and see if that works.

Remove the shower head turn on the water see if the water flows good if good flow the problem is in your shower head clean all the debris and install the shower head you will be Ok, good luck.

John