<s>[INST] A few months ago I developed what my dentist called extreme jaw disfunction.  I had a night guard made for my lower teeth.  About 3 weeks after wearing it my neck started to crack when I moved it either sideways or even up or down.  Sometimes I get a star burst feeling in the back of my head after a loud crack which can be heard across the room that I sit in.  Sometimes I have a light headed feeling too.  Do you have any information about this.  I am seeing a cranial massage therapist whom I am hoping can help me.  Thankyou. [/INST] Hello, Your night guard is designed to prevent some stress to your jaw and preserve your teeth. Are there other dental treatment recommendations made by your dentist to ad Chat Doctor.  You can consider seeing other dental specialist including an oral surgeon and orthodontist. X-rays and scans may provide additional details for a diagnosis.  I am concerned that you may at risk with some nerve damage in your neck. This may require an evaluation by a neurologist or orthopedic doctor. Do you have a history of any back or neck trauma? This can include a fall, car accident or sport activity. A chiropractor may offer you relief and take X-rays for diagnostic information. Anti-inflammatory medication may assist relief for muscle tension. I suggest you discuss additional steps with your dentist and the massage therapist. Thank you for your inquiry. I hope you feel better soon. I am available to answer additional questions if you can provide your medical history and further description of your condition. </s>