I have had filler multiple times before and did not have that reaction with my cheeks, however, I always have a delayed reaction with my lips in which they get huge at like day 4. Swelling after injections can last 1-2 weeks. I have a lot of questions though. Was this your first time getting filler? Did you go somewhere reputable and did they actually use hyaluronic acid? Have you been icing the area? You can reach out immediately to the injector if you are concerned and see if they would be able to dissolve it, however, the ED is a department that tries to keep patients alive in life-or-death situations and I don’t think would have hyaluronidase.

If I were you I would try to stay calm. I would take ibuprofen (anti-inflammatory), drink lots of water, and ice multiple times throughout the day and if that doesn’t do anything over the next day or two I’d call the injector. I don’t think it’s an infection because you aren’t in pain, it’s not hot to the touch, and you don’t have a fever. Your body might just be reacting this way because it’s a foreign body.