I bought my first inversion table like 10 years ago. And the reason for doing so was the same that brought you to my website, pain in the back. For the last few years I only use my inversion table sporadicly, as my back has gotten significantly better. I wouldn´t contribute my healthy back only to the inversion table, but it played it´s role.
The most important thing to do is listen to your own body. Try some different things and see what works best for you!