I am 18 year female with an extra lumbarrib on the right side of my stomach,after exercises i feel slight pain while touching rib or muscle under it?

Ouch!: If you look at an artists drawing of the ribs, you will see alot of connective tissue, especially in the area you are mentioning. This tissue can get inflamed. In my practice I use heat and a good anti-inflammatory cream. Ocassionally I will need to do trigger point injections to take away the pain and inflammation. If this does not help, let me know and I will pass on some other treatments!