11 days post BBL. I'm concerned about a red lump on buttock -- what could this be? (Photos)

Ive had this hard mass on my left buttock since day one. Even in my pictures the nurse took immediately after transfer there was a slight hump. Im hoping its just an area where more fat was transferred and is taking more time. My other cheek is starting to soften and this one feels like it is reversing. It feels tight when I bend over and is painful. The the left buttock started becoming red on the sides two days ago. I am currently on antibiotics. What could this be?