around here, subcutaneus anthrax has a similar syptom, however I will say it is a bug bite of "some" kind. and a neighbor here was treating for brown recluse 2 weeks ago, when the puss spot didnt show in 25 hrs assumed it was something else. The main concern is so near the lymph nodes as Ashton pointed out. A repeat or any other symptoms will make a trip to the doc mandatory just in case it is infectious.
thanx,
bill