What are some reasons my right side hurts sometimes especially if I lay on my back the pain gets worse?

Back/Side Pain. Positional pain in the back/side is most commonly a result of muscle problems, but could be stemming from the spine as well. It makes a difference where the pain is located as well-- chest wall vs abdomen. Regardless, if symptoms are worsening or changing, you should have an evaluation. Certainly any tenderness or "deep" pain should be looked into more urgently. Hope this helps!