Should I Be Worried about a Lump in my Upper Left Butt Cheek 5 Days Post-Op BBL?

Lumps are normal for several weeks so try to remain calm and give it some time. Thank you for your question and good luck.

It is too soon to determine if in fact you will have a problem like fat necrosis. There are too many factors at the moment that will need to be taken into consideration. Certainly, you need to talk to your plastic surgeon and make sure you are not having an infection that can turn into an abscess.

Hello dear!!
Thanks for the question and provided information as well.
You are still early on the healing process, it can take up to six months to see your final results, so please be patient. At the stage you are in, inflammation and irregularities are normal.
If you have any concerns, please follow up close with your plastic surgeon.
Good luck :)

Hey SexyLibra
This may or may not be anything to worry about.  There are several possible explanations.  This might be a collection of fluid or blood.  It could also be an area of swollen fat or possibly infection.  It is definitely something that you should have checked out by your surgeon.
As far as it being "Rejected Fat Cells".... That doesn't happen.  Either they live or they die.  Your cannot reject your own fat cells.   

After fat transfer to the buttocks the presence of a hard lump is not normal. See your doctor ASAP.

That could be fat, could be fluid and could be infection