Hello & welcome,
Restricted mouth opening accompanied with the pain in gums indicates the presence of erupting third molar or wisdom tooth.
This is more likely to be seen if the wisdom tooth is partially erupted in oral cavity thereby creating the gap between the tooth surface & overlying mucosa.
When food debris gets accumulated within these gaps, the flap or overlying mucosal covering becomes infected.
If infection spreads in nearby space, then naturally trismus
developes restricting the mouth opening less than normal.
First visit your dentist
& get an x-ray done to diagnose the presence & position of any impacted wisdom tooth
. Treatment will done as per the findings.
Use of antibiotics & anti-inflammatory drugs in conjunction with painkillers is vital in such case but they should be administered only if prescribed by your dentist.
Avoid hot fomentation or intake of hot drinks like tea & coffee as these may initiate swelling in the third molar region
There is no relation between reducing food intake or herbal pills & reduced mouth opening.