I have recently developed a musty smell coming from the pipe the washer drains into.
Several months ago I was having a problem with the water in my toilets boiling up and over when the washer drained. This has not been an issue in several months but I am afraid they are related??

Is that stand pipe trapped, it should be. You have a partially blocked drain and the sooner you rod it out the better off you will be. They are related but not directly.