What is the ball i feel under my left rib cage?

Difficult to say!: You should see your pcp as you need to be examined and the 'ball' needs to felt and seen. It could be a cyst from skin contents, a fatty tumor, cyst from the joints of the ribs, or be an enlarged organ from the abdomen. Depending on the exam and your history, testing will be organized to determine the cause for it and treatment decided and implemented.