My back hurts...idk what else to do?

so at the beginning of august we started summer band (yes, u r reading something written by a major marching band geed), and about a week later my back started to hurt. So, towards the end of summer band I had started to use heat (even bring something to heat up during breaks). Then school started and I finally had to get a brace. Then, my brace got stuck in my locker (this was thurs), and yesterday we had UIL (we advanced!). It hurt so bad at the games on thurs and fri and then again after marching on sat. What did i do? It hurts near my waistband on my pants, and it hurts on both sides, sometimes in my , sometimes near my shoulders. but it's never in my legs, so it's not sciata. and it's warm to the touch, I play the flute, and i have a pretty arched back. (i can fit my whole arm under it when i lay on the ground). Any thoughts? I'll answer questions if u care to look back after u ask them! We have another contest on Sat! Thanks so much!