Go for a check up immediately and get your condition diagnosed. You may have something called oral submucous fibrosis caused due to supari in the paan..
This causes fibrosis and tightening of your cheek tissue, so mouth opening becomes difficult.
But clinical examination is necessary to say exactly what it is.
Next Steps
First thing stop eating paan masala.
Then go for a check up. Treatment depends on what stage it is at. You can start medication immediately. Injections may be needed.
Health Tips
Do warm water gargles and keep your mouth and teeth clean. Please start treatment as soon as possible, and give up the bad habit of chewing paan masala.