My Middle back hurts when i go on trampoline?

we just put up our trampoline my first time on it i instantly went for flips, corks, and rodeos. i went on the next day and my middle back started hurting its like a sharp pain. Im ok when im not on the trampoline. It also only hurts when i go up in the air i don't know whats wrong. Could it be maybe a pulled muscle or pinched nerve?