Thanks for writing to us.
First you should leave all bad habits chewing gutkha completely your condition is called Oral submucous fibrosis
. As you told that you leave all habits its good you have various treatment for this if you facing this problem with strong pain than you should consult with dentist
as soon as possible and if pain is not than you can overcome from this problem with some exercise
Exercise step as follow
1-Open your mouth as much you can
2- Keep your two fingers in between your teeth for 5 min.
3- Repeat this 5-10 times each day
4- After 3 to 4 days try 3-4 finger same as last step.
5- Do this exercise for 2-3 weeks
Hope this helps you.
Wishing you good health...