Hello I am a 13 year old athlete and I recently began doing dips. As soon as I had received my new bar I was more than exhilarated to try to find my max so I can build on that. But almost as soon as I began the 1st dip set I felt an unbearable pressure in my sternum that felt like if I persisted I would tear my chest in half. I've done some research that advised the readers it could be that they/I was doing the exercise incorrectly. I went over the exercise with my older brother who has somewhat knowledge of calisthenics. He said I had perfect form and he couldn't point out the problem. Could it be I have a muscular in-balance in my pectoralis major or that I have some sort of condition?