Your drain blockage is likely caused by fixed matter stuck in your pipe that traditional domestic unclogging methods can’t rectify. We recommend a CCTV inspection to locate and diagnose the drain blockage.
The gurgling sound is more than likely caused by an obstruction in the venting system in your plumbing. The actual sound is from air being forced through the draining water. An inspection of your vents is required.
If you have smelly mud around your home then you may have a very serious issue with a cracked or leaking sewer. It’s important that this is inspected by a licensed plumber immediately and you keep your pets and children away from the site.