We had just replaced our well pump. A lot in my eyes wasn't taken care of like not replacing filters. We had so much dirt coming in the house at one point it broke the toilet, Which still doesn't flush right. Broke the washer, which we replaced. We were told the well needes to settle for a few days the dirt would stop 2-3 days. It continued 1 &1/2 weeks and found we needed a filter on the cold water tank. The question is since the pump was replaced our shower turns from really hot too really cold. You try to ever so slightly move the dials hoping to keep the temp but you still get the extremeties. What can be the prob?

The well has had an encroachment of sand. You may have to get a deeper well.
Disassemble the shower cartridge and using some sort of funneling so water will not go down or inside the wall, turn the water on to flush any sand from the pipes or shower valve body. Then rinse the cartridge and replace. Note how it comes out, put it back the same way. Don't forget to close the shower curtain when flushing pipes.