I have had pain on one side of my neck spreading into my right shoulder over the past few days. it has now caused very limited movement in my right arm specifically moving from vertical to a 90 degree horizontal position.

See a doc: While this could be muscular in nature, it sounds more like a cervical outlet issue that could be disc, degenerative compression of nerve or cord. Appropriate neurological exam and testing MRI, EMG/NCS should provide an exact diagnosis. Then a helpful treatment plan will be generated. In the meantime be certain your neck is supported well during sleep by a small bolster that distracts and supports

Radiculooathy: This is consistent with an impingement of a nerve root by a bulging disc or spur in one of your neck vertebrae. I recommend applying warm compresses to your neck for 20 minutes several times a day, wearing a soft cervical collar when up and around and also in bed if necessary. Taking an anti-inflammatory medication like ibuprofen or naproxen with food should help. Consult a neurologist if not impr