Severe neck pain when turning to the right. what is wrong?

It is most likely : Muscular in origin although inflamed or swollen glands can also be a source as well as a disc or joint problem in the cervical spine or neck. If muscular or even from a disc or joint issue, they tend to get better with time, otc medication, heat, massage ; some activity restriction. If not or if worsening or accompanied by any neurologic issues like numbness or fevers, chills or sweats, see doc.