I have been feeling a pressure on the lower left rib bones and also a feeling of a 'lump'

I have been feeling a pressure on the lower left rib bones and also a feeling of a 'lump' in the lower left lung chamber since long. It is a persisting pressure feeling. Major artery in the left arm also seems strained and little painful. I try to keep my posture straight as far as I can do. But the uneasy 'lump' feeling remains.