Changed water filter approximately 2 weeks ago. Since then, we've had reduced water pressure at kitchen faucet and in shower. I've also noticed there's too much hot water in the shower (I have to turn the cold water almost completely off to get a comfortable temp, which explains the low flow BUT the water pressure is low even at what used to be a median faucet handle setting) and the clothes in the washing machine feel warm after a wash even though I washed them in cold water only. Bathroom sink and outdoor water faucet (only other water outlets) seem fine, both temperature and pressure-wise. I had our furnace cleaned a few days ago and asked the serviceman to check out our problem: He said the well pump was continually running, but then I had my father (a plumber for 40 years) give a second opinion. He said the well pump was fine, replaced the water filter system and the kitchen faucet entirely, which fixed the problem in the kitchen, but has done nothing to improve the shower situation. The shower faucet is a Moen Posi-Temp and is only about 2 years old. I'm about ready to tear my hair out as finances are extremely limited and this situation leaves me quite vulnerable to rip-off artists. Maybe someone can help point me in the right direction by experience?

Sounds like you disturbed some crud built up on the pipe walls when you changed out the filter and now it's blocking the cold water inlet port of the cartridge in your shower. Call daddy back and ask him to open up the shower valve check the cartridge and then, while the valve's still open, turn on the cold water and flush out the supply line. Also have him unscrew the cold water hose to your washer and clean the inlet screen. You might ask him to flush out the water heater when he's there since some crud might have got in there also through the cold water supply. Good luck and say hi to your dad from one old plumber to another. Tom