Costochondritis generally can't be seen on chest X-rays or other imaging tests used to see inside your body. Sometimes your doctor orders these tests or others to rule out other conditions. It looks like you have had some tests already to rule out other problems.
It can be frustrating to know that there's little your doctor can do to treat your costochondritis. But you can take self-care measures to make yourself more comfortable, which can give you a greater sense of control over your condition. To help relieve the pain of costochondritis, try to:
Rest. Avoid activities that make your pain worse.
Exercise. It may seem contradictory to rest, but gentle exercises, such as walking or swimming, can improve your mood and keep your body healthy. Don't overdo it, and stop if exercise increases your pain
Use a heating pad. Apply a heating pad to the painful area several times a day. Keep the heat on a low setting.
Once your pain is gone, continue taking it easy. Slowly work your way back to your normal activities.
It feels to me like you went a bit overboard with the exercise to soon, especially push ups ~ Ouch !