There are a number of causes which can cause such pain.
Tear of the Acetabular Labrum: you can look up here.
Adductor tendonitis: You can look up here.
Iliopsoas tendinitis: You can look up here.
Lumbar disc pain: You can look up here.
There can also be bony injuries like a stress fracture of the neck of the femur or avulsion fractures.
From your description, aductor tendinitis seems the most likely.
You should consult an Orthopaedician for this. AN orthopaedicain will be able to diagnose your cause and you will probably need investigations like MRI. He will also be able to guide you towards the appropriate treatment depending on the injury.
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