Wow that looks nasty! I suppose you are on some infection killing drugs and I'll bet you were told to watch out for blood poisoning (red streaking). I believe the wound is packed so it will heal from the inside out and drain properly. I had a chest tube site get infected and it was packed much like your arm is. I had to change it and clean with sterile water several times a day. I, however, didn't have to worry about the poison from a bite.
I suggest you inspect your 4runner carefully in case you have any more uninvited guests. Perhaps even fogging with some insecticide that kills the recluse and anything else for that matter.