U hv not given any details regarding how,and whn it started.u shd meet Ur doctr asap so that he cn help u with the same..

Have consultation with dentist for cause of reduced mouth opening

Need to check clinically. Visit dentist on urgent basis.

Going by the description that you have mentioned and without a proper clinical examination, you are suffering from trismus which is due to spread of infection from the teeth or the gums to the muscles. Please consult your dentist as soon as possible so that the exact cause of this can be identified and the right treatment can be instituted accordingly. There are other causes of restricted mouth opening and they can be evaluated after a proper examination and detail clinical history including habits like tobacco usage in any form especially smokeless tobacco. Regards.

Please consult a dentist immediately, if the mouth opening has reduced suddenly, there may be an underlying cause of tooth infection like an abscessed tooth or an erupting infected impacted wisdom tooth, which often lead to trismus or jaw stiffness or reduced mouth opening.