Small hard lump injected with Juvederm
Without examining you, it is hard to tell what the lump is. But it could just be swelling, bruising, over filled or scar tissue. Juvederm wouldn't be my first choice to inject a scar on the forehead, but I didn't see you before your injection. The good thing about Juvederm is that it can be dissolved away. I'd continue to follow up with your doctor. Ask if they have experience dissolving it, because that may need to be considered. Was it a doctor or a nurse?
Forehead lump with juvederm
By 2 weeks most if not all of your swelling should be gone. From the picture, it appears to be overfilled. I would go back to your doc and let them re-evaluate you. If you are not confident in there treatment, seek treatment elsewhere by a board-certified physician.
Why have I got a small hard lump behind my scar after Juvederm?
Thank you for sharing your question and photograph. I am sorry to hear of your lump after Juvederm injection but it is difficult to know what may have caused it without an in-person examination. This may be swelling from the injection and absorption of water from the surrounding tissues by the filler material, excess filler placement, or a small hematoma. See your injector about possible treatments such as massage and warm compresses. Best wishes
Filler for forehead scar
If the filler is placed deeper than the scar, it will appear like this. It should flatten with time. Consider other scar treatments such as Infini, excision, laser treatments. They give a better and more long lasting result.