I Am A Truck Driver And Had A Boil On

I am a truck driver and had a boil on my neck. It drained just fine and is almost gone but now I have one on my right back shoulder. The redness is spreading out and the pain is most of my shoulder. How .ca. I get antibiotics to treat this? I've tried to open it up in the shower and by digging in it. Neosporin is kind of helping