Hello-Can anyone point me in the direction of building a new trailhead that would be in addition to the one I already started?

Hi @Bernie Montoya, you can do that by visiting https://trailhead.salesforce.com and clicking on the sign-up at the top right corner.

You can signup by any of the following

or even with a salesforce org

If you want to keep it separate from the current account then just make sure it should not be related to the means through which you created the current Trailhead.

In future, you can merge your trailhead accounts if you want.

Thanks