Sounds like the medial collateral ligament (MCL), which you mentioned your doctor said.
Just wondering if the "C" word was "Cruciate", as in Anterior or Posterior Cruciate ligaments? (ACL/PCL)? Either way, the MRI is the key......
I wish you the best of luck, and hope you can heal without surgery!
And I agree with Kylie, call back and get the details!
Let us know..... Good luck.