Fully agree with @makemesmart . I hope you can find the reason for your back pain and resolve it before it comes back and impacts your quality of life. IMHO, decision you wish to make largely depends on this potential problem. There is no point in even contemplating dropping out of your current school to pursue music if after a while the back pain will come back and keep you from doing what you love doing. Wishing you all the best of luck in getting to the bottom of that issue.