Knee Pain to Hip

Hi! So I have been training for my first marathon. I have ran a half before so I’m use to the training process but not nearly as high volume. The past few weeks I have been experiencing inner knee pain that has escalated into my hip/groin area.

I have tried stretching, cross training to strengthen the muscles but the tight uncomfortable feeling still remains in my groin. Any suggestions on stretches and things I should do? Is this a issue in which I should see a doctor???