Abscess in butt cheek 3 months post op BBL (Photo)

2wks ago I developed a hard painful lump in my right butt cheek. I had my BBL done in October with no issues up until now. Went to the emergency room and they said it was cellulitis and an abscess forming and gave me Bactrim and cephalexin. First the lump was hard and you could only feel it but not see it. Almost done w/ antibiotics and it looks worse but feels better, in the center of the lump it's now soft. Is this an abscess is it gonna go away? Should I go back to ER? Doc is in Miami