I am 16 years old, very fit, cross country runner, track athlete, and soccer player. I've been active my whole life. Recently when i started middle school i began to have pain lower rib pain on my right side and upper rib pain of my left side. I have certain time that it happens, i can be running, walking or just sitting in class and it just starts to hurt really bad. i usually just put pressure on it and then it goes way in about 5 seconds but its pretty frequent about 2 times a day. I've never had anything happen to my ribs like injuries or anything. I had a kidney surgery this summer but this pain had been happening way long. would could this be?