I have what feels like a large lump on my left side under my rib cage, but not behind it. it feels like a ball and it actually moves.

Need to examine: It is not feasible to provide a meaningful opinion without examining you, however, what you described suggests a benign tumor of fat. lipoma. You may consult your doctor at your convenience to ascertain if it may warrant removal. Wish you good health! - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex.