Constant left posterior rib pain. rest does not relieve. feels like something trying to poke out. when breathing feels like lung pushing something?

Please see a doctor: You really should be examined by a doctor who can listen to your lungs and examine your back to check if this is related to a lung problem, a rib issue, or a muscular problem. Then they can help with the proper treatment.

Need to examine: It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated.