A hamstring injury typically causes a sudden, sharp pain in the back of your thigh. You might also feel a popping or tearing sensation. Swelling and tenderness usually develop within a few hours. You may also experience bruising or discoloration along the back of your leg, as well as muscle weakness or an inability to put weight on your injured leg.
When to see a doctor
Mild hamstring strains can be treated at home. But you should see a doctor if you can't bear any weight on your injured leg or if you can't walk more than four steps without significant pain.