hi, thank-you for providing the brief history of you. As to let you know one of the primary act is thorough musculoskeletal assessment is advised and also the cardiac clearance before undergoing gym. It is on a safer side to get clearance and then proceed. As mentioned by you that you have a pain under the ribcage or below it, it could be most of the time a muscular pain. Due to overtraining there will be a sudden mucle spasm due to stretch contract mechanism on the elliptical. Taking a rest with hot water fermentation should reduce the pain and after 3 days you can go back to gym. Also, if the pain doesn t come down, than taking up a thorough musculoskeletal and cardiac assessment is advised on a safer side. Since you have discomfort on the right side, the worry is less, may be just a muscle spam on the right hypochondria. It should subside in short time. This is on of the common injury in gym, as the body is not prepared to undergo the stress & strain on the muscles. Undergoing slow and steady training under guidance will help avoid such injuries in future. Regards Jay Indravadan Patel