I live in a two 1/2 story house with my kitchen on the top floor and the master bedroom on the lower floor. Yesterday, my garbage disposal contents started coming up in the drain of the bathtub. Any idea why this happened and what I can do to fix it? We have no other plumbing [...]

This has happened within two days of each other so am fairly convinced a problem with my filters/drains?? But not sure where to start.

We moved into a house a few weeks ago and we have noticed a mold smell coming from our double-sink. (it goes away when we plug the sink)
The house was built in 1996. Is there a treatment available to get rid of this problem?
Thank you!