What would cause my Mac's trackpad to go absolutely haywire?

Obviously I will be taking it to the Apple store to have it looked at, it’s just that isn’t really convenient right now and I’m curious as to what’s going on in case anyone else has experienced this.

Essentially, the trackpad has become useless on my Mac as of a couple hours ago. Moving around the cursor causes it to randomly click and select things, scrolling is completely defunct. Restarting the computer hasn’t helped. Is there any way to disable the trackpad so I can use a Bluetooth mouse instead? Because even that isn’t working as long as the trackpad’s madness continues to prevent the mouse from taking over.

Ugh…