What can i do to ease my backpain?

Im 17 and ever since i was 12 (my 3rd year into soccer) i have had constant backpain mainly in my lower back and in my higher like neck and shoulders almost. And iv done everything to find out whats wrong but all doctors say that theres nothing wrong! So what can i do to just relieve it some? Medications are not an option, becasue nothing works.