A hamstring strain, also sometimes called a pulled hamstring, happens when one or more of these muscles gets stretched too far and starts to tear. Hamstring strains can be mild, with little pain and a short recovery time.

Symptoms

• Sudden and severe pain during exercise, along with a snapping or popping feeling
• Pain in the back of the thigh and lower buttock when walking, straightening the leg, or bending over
• Tenderness
• Bruising
• Oftentimes, a "pop" is heard or felt by the injured athlete
• Mild hamstring strains may not hurt too much. But severe ones can make impossible to walk or even stand.

Diagnosis & Treatment

Physical exam is done by the doctor, she will check your thigh for swelling, tenderness, and bruising. ...
If the doctor thinks you have a severe injury, you might get an X Ray and MRI done.An ultrasound is another test that produces a detailed image of your muscles.
When you first visit a Physiotherapist for treatment of your hamstring strain, he or she will conduct an initial evaluation to gather information by Discussion of your injury and health history and determine the best treatment.
Your Physical therapist will use the results of the evaluation to form a specific plan of care for your hamstring strain rehabilitation. He or she will also work with you to set reasonable goals for hamstring rehabilitation