lump usually does not cause a sore rib cage
. Persistent pain in the area can be either due to costochondritis
which is otherwise known as Tietze's syndrome and the pain occurring due to this is aggravated with exercise and deep breathing or due to chronic hyperacidity
which can cause a vague pain in and around the rib cage. Distinguishing between these two entities is extremely important since commonly prescribed analgesics would help in improving the pain from costochondritis but would aggravate that resulting from hyperacidity. No special investigations are required but avoidance of exercise and control of hyperacidity (if any) would help in resolution of your symptoms.