Be aware of habits or patterns of jaw use   Avoid tooth contact except during chewing and swallowing Notice any contact the teeth make Notice any clenching,grinding,gritting, or tapping of teeth or any tensing or rigid holding of the jaw muscles. Check for tooth clenching while driving,studying, doing computer work,reading, or engaging in athletic activities and also when at work or in social situations and when experiencing overwork, fatigue or stress. Position the jaw to avoid tooth contacts. Place the tip of the tongue behind the top teeth slightly apart; maintain this position when the jaw is not being used for functions such as speaking and chewing. Modify your diet   Choose softer foods and only those foods that can be chewed without pain. Cut foods into smaller pieces; avoid foods that require wide mouth opening and bitting off with the front teeth or foods that are chewy and sticky and that require excessive mouth movements. Do not chew gum. Do not test the jaw himself. Do not open wide or move the jaw around excessively to assess pain or motion. Avoid habitually maneuvering the jaw into positions to assess its comfort or range. Avoid habitually clicking the jaw if a click is present. Avoid certain postures   Do not lean on or cup the chin when performing desk work or at the dining table. Do not sleep on the stomach or in postures that place stress on the jaw. Avoid elective dental treatment while symptoms of pain and limited opening are present. During yawning, support the jaw by providing mild pressure underneath the chin with the thumb and index finger or with the back of the hand. Apply moist hot compression to the sides of the face and to the temple areas for 10 to 20 min twice daily.

U need an x ray of TMJ to see the exact reason of pain and grinding sound while opening and closing of mouth. Sometimes it is due to stress but sometimes it can be due to degenerative changes in ur bony part of TMJ or due to abnormality of  disc inbetween the TMJ. Visit an oral and maxillofacial surgeon for the same

Plz condult dentist for proper diagnosis and treatment.

Visit a oral surgeon.dr will suggest you an x-ray to view TMJ.depending on that treatment can be decided