Thanks for your consult at DoctorSpring.com.
Your problem most probably is related to the wisdom tooth infection.
The wisdom tooth or the third molar tooth very often in all adults erupts b/w
16 to 25 years. in those patients that it doesn't appear during this period it remains inside the jaws, just behind your molars it starts to cause pressure on your adjacent teeth sometimes and sometimes gets infected and therefore causes severe pain in the jaws and associated difficulty in mouth opening.
So get an OPG xray done very soon and consult an oral and maxillofacial surgeon for its removal.
If it is not related to the third molar tooth, it could be a soft tissue growth due to infection, which the surgeon will be diagnosing.
For time being you can start a dose of antibiotics such as Ciproflixacin with Tiidazole and painkiller like Paracetamol with muscle relaxants.
Hope this helps, please feel free to get back with follow-ups.
Orthodontist and Clear Aligner Specialist(Germany)