Hi there,
Thank you for your question. Hamstring issues are very common in anyone who takes part in running sports. Often it from an overload over the muscle either at the muscle/tendon junction, tendon/bone attachment or within the body of the muscle itself.
In situations where you develop sudden pain in the hamstring, the first thing to do is NOT to stretch. This is because if you have torn any of the areas I mention, it can make this worse. The best thing to do is to offload the muscle with crutches, apply ice and a compression in the form of a tubi-grip, and then seek help.
A Sports Physician/Physiotherapist will assess you and many can perform a same-day ultrasound assessment. This can establish the location/nature of the injury and then they can advise you on the best course of treatment. This might be as simple as offloading, rehabilitation with gradual loading, or it might require surgical intervention.
I hope this helps.
BW
Dr Dinesh