Hi there ~
I understand your concerns. However having a sore neck as a result of "auto-fellatio" would require you to get an imaging study of your neck, i.e. an x-ray both AP and Lat. views as well as an MRI
to determine if you have had a spondylolisthesis
. If you have a diagnosis you need to be treated for the same. I would recommend that you see an orthopedic doctor as soon as you can. I hope this helps.
Take care and have a lovely day!