Nursing is very intense both the coursework and clinicals, but if you want another major take some of these elective courses in that field and see if you can do both. Start with 1 or 2 classes as your nurse schedule allows since a BA/BS requires electives anyway. Probably easier to pursue a minor.
I took classes in international relations before I became a nurse and did enjoy the classes and I suppose they were useful in an offhand way as you care for patients of many different nationalities and languages as a nurse. Spanish is obviously the most practical language in healthcare these days!
I love learning so I understand your desire to pursue another major, you just have to take it slow and see if you can handle the nursing coursework first and of course can you afford the extra time in college to finish a second major as it is for your personal fulfillment and most likely will not lead to a higher paid job as a nurse.
If I had the money I would love to go back to school, but practical day to day living expenses preclude this for me. However with the internet and libraries you can study anything under the sun if you don't need the official college credit. They even have actual IVY League coursework on the internet for free to essentially audit if you were interested. Truly the internet is like having a virtual encyclopedia at your fingertips and now with the Kindle
you can have books at your disposal as well. Even some public libraries are starting to offer free books thru Kindle!