I Have A "lump" In My Groin Where My Leg

I have a "lump" in my groin where my leg meets my private area. This "lump" is in a line shape and is dark purple in color. This appeared about 6 months ago and started draining a lot of dark blood and will only stop when pressure is applied.
It went down but not completely away. Then fills up again and starts draining again dark blood. There is never any pus. It does hurt.
What is this? Doctors put me on antibiotics but it never goes away.
What could this be?