Job References: Advice Needed on How to Get My Second Nursing Job

Hi All,
I'm three years into my nursing career and I feel stuck. This was my first job so I have no previous boss or job contacts to use for references. There are no managers at my current job who would not fire me or take serious umbrage if they received a call or letter revealing that I was looking for work elsewhere. I wasn't that close with my professors at nursing school, except 2. One is no longer there and besides, I haven't kept in touch with them and feel funny asking them if I can use them as a reference since I have not gone back to visit them. I have friends at work but is it possible to use coworkers for job references? There are possibly some clinical coordinator level staff who would do this for me but I am afraid it is a mistake to let anyone at work know I am looking to move on. I am stumped on who to use for references. Did this happen to anyone out there? What did you do to get what you needed to keep moving forward in your career? I very much appreciate anyone's thoughts on this subject.