I got bumps in the bottom of my cheeks and nasolabial folds after fat grafting. Can it be swelling/or fat slipped down? (Photo)

Hello, it is unlikely that this is swelling at this point, and it could be the fat causing contour irregularity. It is difficult to say without seeing you in person. The good news is that there are reliable techniques to remove fat graft, and it can often be taken care of under local anesthesia. Best of luck.

Transferred fat typically does not "slip down," as there is not a wide open space for injected fat to simply "slide around" in.  However, if you have undergone an ultrasound procedure by a qualifed operator, and he is able to detect fluid density, it may be possible that you have cystic collections of probably fatty/oily fluid in your tissues that can certainly create swelling and fullness.  Sometimes this can happen, especially if improper technique in which larger "blobs" of fat were injected in a specific site, allowing the fat cells to rupture and their fatty oil to coalesce.  Fifty cc's is a rather large volume for just the cheeks, or even the cheeks, nasolabial folds, and pre-jowls combined, and I wonder about the technique used and the volumes with each injections.  When this happens, it is called "lipoid cyst" formation.  It is not a medical urgency, but as you can see, it can create an undesireable contour until addressed.  The best approach at this point would be to return to the ultrasonographer and see if an ultrasound guided aspiration of all of the fluid cavities can be accomplished.  Once that is done, and the tissues have "settled down" to baseline, a new, truer assessment can be made of the actual tissue contour and  any further treatment that may be needed or desired.  Best of luck.