10 months post-op, large lump after BBL. I felt a hard quarter size nodule within the lump. Can you please explain?

Hi Drs, Its been 10 months postop BBL. immediately post surgery I had this lump on my left buttock & I was told to wear extra compression around it. It’s been 10 months postop it’s still here, my Dr said it’s becuz fat around has died. For the past 2 months, I’ve had pain around the lump, which feels kinda like sciatica pain. Yesterday, I sent to feel the large lump, but felt a hard quarter size nodule within the large lump. Im scared, can u please explain?