I had a BBL done about 10 months ago. I have a hard lump in my right butt. What should I do? What can this be?

There are three possibilities that can cause a hard mass or lump after a BBL. It could be a seroma, a hematoma, or fatty necrosis. If it is a seroma or hematoma it could be drained, these are collections of fluid or blood. If it is fatty necrosis it means that some of the fat that was injected didn't survive and left scar tissue. It is not harmful, but if it bothers you, it needs to be excised, lipo will not work.

Without an examination and appropriate evaluation no one can tell you what this represents or what your treatment options are.
A very rudimentary evaluation could include and ultrasound to determine if the mass is liquid or solid.
If it's liquid it could possibly be drained surgically or with a drain(thin silicone tube connected to a suction bulb)
Sometimes chronic fluid collections develop membranes call capsules.
When that's the case and sometimes it requires removing the capsule surgically.
If the lump is solid it may need to be removed surgically or left alone depending on which would serve the patient best.
Your plastic surgeon should be able to manage this.
Nothing wrong with getting a second opinion.
Best,
Mats Hagstrom M.D.