When is a bite more than a bite?

E was complaining about a bite on his leg. I decided to check it out. This is what I found. 

The circle around the bite was rock hard and there were streaks coming out from it that were also rock hard. Everything that was red was very tender.

The area immediately around the bite was 1" diameter. The entire red spot was 3 1/2" diameter.

My question was: Do I take him to Urgent Care b/c it is a Friday night and the Dr. is already gone? I decided no. Yeah it is a bad infection, but would the UC just give him an antibiotic just to be safe or did he really NEED it. With E's immune system so messed up already, we have to be careful about antibiotics that are more than what he really needs. Last summer he got ant bites that looked almost as bad as this and they just put him on an antibiotic without a second thought.

The only product we have for cleaning infections/cuts is alcohol. Poor guy. He was really brave, though. He only whimpered a little. (Notice the battery in his hand? I had him squeeze it while I applied the alcohol. It seemed to help distract him a little.) We finished it up with Neosporin and a band-aid. We repeated the procedure in the morning. This time he said the alcohol was tickly. The redness did go down some, so I know it is working. The only bad thing is that we found 5-6 more bites, all red and swollen, though not as bad as the 1st. So, I guess we just keep chugging along with our routine with a lot of bites and see how he does.