"Pimple” like bump on my lip 2 weeks after filler. Any idea what this could be?

It has been two weeks since I had fillers. It is still stiff and a bit lumpy on the bottom but seems to be healing properly. Two or three days ago I started to notice a “pimple” had formed on my lip and there is black on the tip of it but it seems to be inside of the pimple. Any ideas on what this would be? It also feels like a pimple and hurt but is no longer hurting.