I have changed careers through the life, but always pursued in the field I like and have both earned my undergrad and postgrad in it. I changed job this year after 8 years in the same industry as I felt that I could not learn anything new and was not challenged enough. Career change is often hard. I left my job that had great team and I was respected leader. However, I knew I can do better and this was a reason for the change.
You should never leave job until you have something lined up. Job is money and money is security. The career path depends on your abilities, interests, and opportunities. I love history, but there are not jobs in it, so it is my hobby. Many people go into field to find out that there is no demand. If you consider nursing, ask what you want to do. It is still broad field. It is extremely demanding field that can cause burn out. Some field could allow you to choose specialization in nursing, occupational therapy, and so on. You can also consider going for some specialist and technician. One of my friend changed career in later part of his life as radiologist and he loves it. Look into the job market on line and what skills in healthcare are in demand. Figure out where you can stand out. While many people and many news say that nursing is always in demand, there are 200,000 in that field entering the job market every year.