Hello and welcome to ask a doctor service. I reviewed your query and here is my answer. The ball like mass in your naval will be most likely lipoma if it is movable and not attached to the skin and will be soft which is completely unrelated to the other two symptoms. However the other two symptoms may be related as the chronic back pain may cause nerve compression if there is disc problem. Do you have problem in standing from sitting position or vice versa? Have you done x-ray of your spine? While lying down, and raising your left leg straight, does it cause pain in your spine area? You may have sciatica but can be confirmed on investigations. But for now you need to do exercise of back. But for now avoid all the activities which involves bending forward frequently. Hope i answered your question. Feel free to ask if you need further assistance. Thanks.