I just had wisdom tooth removal(all 4). i'm now on day 4 & have this hard lump on my lower jaw & cheek,went to er & my dentist.both said no infection.

Swelling?: This might be typical post operative swelling. If the lump is next to where your wisdom tooth was and it was a complicated extraction it may be a subperiosteal swelling and should eventually go down. You may want to apply a heating pad a few times a day to help it go down. Stop if it gets worse from the heat because if that happens it is most likely an infection.