What Causes Persistent Pain At The Bottom Of The Rib Cage?

Hi dr, i have a constant pain in my left side of my stomach bottom of rib cage. The pain is not severe but i am unable to brathe freely. i cannot run too far i start gasping for breath and my brain contracts. i am a mild smoker but a heavy tabbaco chewer. I snore a lot at night and in recent months I am unable to sleep. I feel very sleepy during the day but cannot sleep in the night till late hours.