i had a tooth extraction, my lower left wisdom tooth,  while the area on the inside of my mouth is not sore and has healed well, i have a very firm lump in my cheek tissue.  It is about size of a half walnut and doesnt hurt unless i put pressure on it.  I do not have a fever or feel bad at all and it has been 5 days since the extraction.  My jaw has minimal pain, and most of the swelling is gone.  What could this lump be?  I have been on penicillin for a day now.
HI. Most probably this must be a hematoma at the injection site. This is less likely to be an infected collection or so. Consult the Dentist and if this is hematoma, this will get resolved on its own. You are already under an antibiotic cover so nothing to worry about.