MCL Injured 9 weeks ago. Problem

I was diagnosed with a grade 2 mcl tear 9 weeks ago. I did Physical therapy for it. MRI was taken and confirmed mcl tear. I resumed normal activities about 7 weeks after the injury and now all of a sudden I woke up the other morning and I now have a sharp pain along my mcl. it only starts to hurt when i bend it to at least 120 degrees then when i get past about 165 degrees the pain stops. As you could imagin it hurts to walk. although for no reason what so ever it will sometime not even hurt at all. The pain is a lot different from the pain i first had with my torn mcl. its super sharp and stiff feeling now. Besides the sharp pain my knee feels strong and stable. Does anyone know what is going on here?? What should I do? keep resting it??