I Have A Sore On My Arm And I Am

I have a sore on my arm and I am wondering if it is a spider bite. I'm fearful that it maybe a brown recluse. It started approx 10 to 14 days ago with a spot that appeared to have 2 deeper indentions almost like fang marks. It then formed a dime sized puss place and the top of the skin came off. That part is deeper, red and drains fluid and puss. Then other places formed near this as pustule places and the skin come off just by touching these. It looks swollen further around all these and the swelling seems to be going further down the arm. I've bee covering it with sterile gauze and antibiotic ointment. What should I do