Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Common causes for stiffness may be due to sleeping abnormal position, Turning head side to side during activity or sloughing poor posture or cervical degenerated disc or cervical herniated disc or cervical osteoarthritis etc. Until examination is done it is difficult to say what it is. Wearing a cervical collar to immobilize a stiff neck is not advised. Rather, an individual with a stiff neck should try to stick to normal activity levels if possible, especially after the first day or two. cases where pain is significant, an individual may want to use an over-the-counter pain medication or apply ice and/or heat therapy. If a stiff neck has not shown improvement after a week, it should be checked by a doctor. Also, regardless of how long it has lasted, a stiff neck accompanied by any red flag symptoms—such as a fever, headache, nausea or vomiting, or unexplained sleepiness—should be seen by a medical professional immediately. Hope I have answered your query. Let me know if I can assist you further.