No control over the cursor. Jumps all over page. Unable to guide

Most likely you have a hardware issue with your laptop. Either the Trackpad has failed or the Battery in the laptop is beginning to swell pushing against the Trackpad which can also cause erratic behavior. Check carefully to see if you notice the Trackpad being pushed up or if the Bottom Case is separating from the rest of the laptop or it the laptop doesn't sit properly on a flat surface. If the Battery is starting to swell, then you want to immediately unplug the charger from the laptop & power off the laptop as the swelling will only get worse. Take the laptop to an Apple Store or an Apple Authorized Service Provider to be examined. If they are not open in your region, then click on the "Contact Support" link at the top right of this page to see options for your region. In some regions it is possible to mail the laptop to Apple for the repair.

Depending on the Trackpad failure sometimes you may be able to reboot the computer and use an external mouse/trackpad instead as long as you do not touch the built-in trackpad. I think sometimes touching the built-in trackpad will trigger the issue and once triggered an external mouse/trackpad won't help.