Hi, I Had My Lower Right Wisdom Tooth Removed 4

Hi, I had my lower right wisdom tooth removed 4 days ago. On the 2nd day after the removal I developed an infection and my right side of the face was very swollen and filled with pus. I started antibiotics, amoxicillin 500mg x 3 per day plus iboprufen 600mg for pain. That day I started pressing on the outside of the cheek and drained a lot of the pus that way. Now, after 48 hours of taking amoxicillin, the swelling has gone down and no pus is coming out but there is a hard walnut size painful lump on my lower right jaw. The question is what is it? Since there is no pus, I assume amoxicillin is working but what could be that painful lump? Thanks for your advice.