Hello and welcome to e health forum.
The painful lump described could be due to costochondritis.
Costochondritis is an inflammation of the cartilage connecting the ribs to the sternum (breast bone). It presents as a sharp pain in the affected cartilages, and may be associated with redness and swelling too.
Pain caused by costochondritis may mimic that of a heart attack or other heart conditions.
The proper diagnosis is usually done by clinical examination, and tests like X ray are needed just to rule out other causes like rib fractures.
Taking medications like Ibuprofen (Advil, motrin) can help in relieving the pain.
In case, they do not help, you may need treatment with prescription medications like antidepressents to control the pain.