Following cervical surgery, my thumb went completely numb. Why?

Hi doctor,

I had an MRI last year, which indicated a herniated disc and stenosis at C6-C7 left. So, I had cervical surgery ACDF. Still, l had pain for a couple of months and the MRI showed to my dismay that I still had stenosis with displacement of the C7 nerve root. Also, it showed that C5-C6 protruding disc and partial corresponding osteophyte with no nerve root displacement or stenosis at C5-C6. Before two months, I elected to go with a posterior cervical foraminotomy and was told the C7 nerve was then released. Four days after my second surgery, my thumb went completely numb on the top half and has stayed that way. The thumb is normally associated with the C6. The surgeon told me that sometimes radiculopathy overlaps and I just have to live with this. Doctor did not want to follow up with an MRI. I thought at least an MRI should be done just to confirm why the numbness may be there. Can you please advise?