One of our toilets just started making a loud, terrible noise after you flush it. We recently had a new toilet and tub put in out other bathroom, and the toilet replaced with our other one. Why would it start doing this now?:(

Toilet makes nois for two reasons loose washer at end of stem inside the angle valve, or dirt inside the fill valve.

To isolate the problem next time the noise starts back off the angle stop located under the tank counterclockwise until the noise stops, if it doen't then problem is with fill valve, please see the images below and tell me wich fill valve do you see inside the water tank and ew will tell you what to do. Thanks.

John