Black blisters from my faja? I️ started noticing these blisters three days after my BBL. What are they?

Blisters in the early post operative period after a BBL may be due to friction from a poor fitting garment. I would recommend you visit with your plastic surgeon so that he/she may evaluate you and address your concerns. Best wishes. 

Thank you for posting your interesting question. Black blisters are never a good sign following liposuction or a BBL and most likely are due to excessive compression on the skin. I do not recommend Fajas for this reason. A regular post operative liposuction garment which are designed to allow some swelling after these procedures work best and rarely produce blisters. I recommend that you immediately see your Board Certified Plastic Surgeon that performed your procedure to take the appropriate actions and discontinue wearing your Faja. Best wishes, Richard Wellington Swift, M.D.

It is hard to give you specific advice without at least seeing photos. You should contact your PS immediately. "Black blisters" may be from the garment being tight and rubbing against your skin or it may be secondary to tissue ischemia or repetitive trauma from liposuction (more common with vaser or laser lipo). 

Without more information to you what you were experiencing it with this baby.
That said black skin or black blisters could be something very serious.
You should contact your plastic surgeon ASAP.
Best,
Mats Hagstrom M.D.