I got a lower wisdom tooth extraction 5 days ago and the swelling has seemed to gone down completely except for a hard, ball-like lump in my lower jaw, which makes my cheek protrude and also makes it hard for me to open my mouth. the dentist said this is

Extraction: Sometimes there is trauma or bruising of the muscles during the extraction and this may be the reason why it is still hard to open your mouth. This will take some time to heal.continue to follow up with the extracting dentist and follow their post op instructions. If your concerns are not being addressed then consult with an oral surgeon.

Possible Infection: The late swelling coupled with difficulty opening your mouth could represent a postoperative infection. You should return to your dentist and/or surgeon for evaluation and any recommended treatment (antibiotic and/or incision and drainage of the infected area).