Why does it hurt really bad under my right rib cage to breathe and move? It has been going on for a couple of days now too.

Maybe Pleurisy. Many things can cause pain under the rib cage that hurts with pain and breathing, but pleurisy comes to mind. This is inflammation of the lining of the lungs. This can come about due to infections from uris, or conditions that create inflammation in various places of the body. Injuries can cause bone bruises and costochondritis.Anything affecting breathing needs some attention.Can try nsaid.
? Pleurisy. This sounds like it could be irritation of the lining of chest, which sometimes occurs with viral or bacterial respiratory infections. It can also occur from pulmonary embolism. If you haven't had symptoms of respiratory infection, then you should see your doctor to have a blood clot to the lung excluded.