I Have A Large Lump In My Thigh. It Started

I have a large lump in my thigh. It started 3 weeks ago with an inflamed area. My doctor put me on an anti-biotic. Since then a boil type lump has opened up and is weeping. The puffy area around this lump has gone down but the initial lump is still there. It's about 3" long and 1" wide.