We live in a 2 year old house with well water. Our water pressure, particularly in the upstairs showers, stinks. It seems to have gotten progressively worse over time. If you run a second source of water with the shower running (ie a faucet), it dribbles out. We have a filtration system, the water has been checked, and all pH/metal levels have been ok. The well guague reads between 40-60psi.
The only thing of note with the well--we had air in the pipes twice last winter that required the well company to come fix a stuck valve. There is no more air in the pipes, but I swear the pressure has been getting worse ever since.
I called the well company and they claim it isn't the well. They say the stuck valve wouldn't cause this problem. The boiler company says its not them.
Look at the water filters. I think you'll find that they have a bypass mode on them. Turn them to bypass. If your pressure problem is solved, then change the filters media out, its clogged. If this doesn't change anything, call the well folks or a plumber out to have a look.
Pictures of filters and well equipment would help.