What are the causes and treatment for swelling flare ups months after Juvederm?

I've had my lips Injected with juvederm a few times. I got them done agaim maybe the third or fourth time a couple of months. However now im battling with swelling flare ups, usually accompanied by a small red rash on the lip line and it does usually feel dry and swollen. I use antihistamine, hydrocortisone bepanthen etc and my lip only ends up getting bigger. It does feel like some product may be in the skin surrounding. My doc doesn't have the dissolving agent. Any advice appreciated.