Thank you for your question and for finding EmpowHER. Unfortunately, custodial work is very physical. As we age, I think it's not uncommon to hear all sorts of creaks and cracks when you move about your day--especially if you spend most of the day moving about!
A similar ASK came in a while back, and the moderator, Alison, gave great information. You may want too check it out: Can Strengthening Abdominal Muscles Help Back Pain?
Additionally, if you haven't been to the doctor in some time, you may want to get checked out to rule out some other causes for your back pain. The doctor also may have some suggestions that will work for you and your particular condition.
Good luck, and let us know how you're doing.