I went to a speech /swallowing therapist, who gave me some very good and easy exercises.
Some as easy as just looking as far left and right several times, each day.
Maybe it will be frustrating at first, but as you stretch out your neck, hopefully you will gain mobility and less pain.
Everything with this cancer recovers so slowly, but surely.
You will recover over time, stay positive.

Enlarged left cervical lymph node in neck on 1/9/18. Male, age 60. Had retired from working as a computer technician and a project manager for almost 38 years, on 7/1/17.
Node was removed 1/16/18 and found to have SCC P16.
Chest xray clean.
Since then, PET/CT, slight activity left parotid, possible malignancy left lingual tonsil. MRI clean.
3 endoscopies, nothing seen.
2/26/18 Larryngoscopy,primary not found.
TORS 3/23/18 lingual tonsil biopsy.,biopsy negative.
Chemo/rads started 4/18/18.