What's wrong with my ?

During a big blizzard I had to help shovel our driveway. I really hurt my and it felt like I just pulled a muscle. I rested and gently stretched but now, months later, it hasn't gotten better, and may have even gotten worse. I have cheerleading and tumbling starting next week and I'm really worried about it. How am I supposed to learn to flip when sometimes I can barely sit or stand? Please help.