Low shower water pressure

Recently, we installed a new water filter in our shower and that action completely changed our pressure. So we changed out the shower head we removed the water filter and purchased a new shower head to no avail. We still are experiencing the low water pressure in our shower, so I'm thinking when my husband removed the old water filter and put in the new one something happened which changed the pressure, any ideas. The water pressure in our main shower has not changed and the rest of the house is fine, it is only in my shower. What are we missing?
Thanks.

It is likely some debris got into the line when the filter was installed and has worked its way to the shower valve. You will need to disassemble the valve, clean it out, and reassemble it. It would be a good idea to check all of the aerators in the house as they may have some crud in them as well. The above is especially probable if you have old galvanized pipes.