Nursing is an extremely physical job! Staffing, especially in LTC, can be iffy so you can't always depend on someone else to be there. And, as you can delegate the lifting and such, at the end of the day it is YOUR responsibility that it all be done. And remember, there is no delegating in clinicals. Most often you are the total caregiver.
I would strongly recommend that you speak with your dr. first. You might be able to build your back up with physical therapy, they are really doing amazing things these days.
I once had a CNA as a resident at a LTC facility. He hurt his back while working there and now is wc bound for life.
We definitely need all the nurses that we can get however you do need to be sure that is a job that is safe for you.