I usually stretch before I start playing badminton. It's nothing serious. I just do what was taught to me in PE class during high school. For the past couple of weeks, I'm experiencing discomfort in my lower back after badminton. Surprisingly no other part of my body is sore or experiencing discomfort except for my back. I can't figure out why it's like that. What do you guys suggest to treat the discomfort in my lower back?