What Causes Severe Pain In Neck And Back Post ACDFI Surgery?

I had a protruding disc in C6 to 7 and had ACDFI surgery at the end of January. I still have severe neck and back pain with the tingling, burning pain down my left arm with weakness in the elbow, wrist and hand. I am now having the same types of pain in my left leg and issues with shuffling when walking. I had another MRI last week that indicate that the C6to 7 has interval anterior fusion with no significant central canal or foraminal stenosis. There is a mild,diffuse disc/ostephyte complex with mild central stenosis in the C5 to 6. I am not sure what this means or if this would explain the pain. My doctor says the pain is residual nerve issues and I start physical therapy 3 times a week. I am not sure if I can handle the additional pain at this time. Should I be concerned about the C5 to 6 issue and I am wondering why it was not noticed in the first MRI 3 months earlier.