Son hurt knee 11/13/14. told possible torn meniscus. waiting on insur. to approve mri, he feels fine, does he still need an mri?

It would be unwise: to advise you for or against the MRI without the benefit of a complete history and examination. A severely damaged knee won't heal normally and could potentially create a life time of problems and disability. Your in-person doctors likely know best for this situation, but if you are not comfortable with their assessment and recommendations, exercise your right to a second opinion locally.