Flair-ups of swelling, hardening & soreness months after injection?

Hello, I have been having episodes in which i wake up and parts of my chin and jaw area have swollen, hardened and are sore. I had juvederm - i think it was Voluma - injected over 6 months ago. It started a couple months ago when I was on vacation overseas. Since then the flair ups have been happening more frequently, and for seemingly no apparent reason, ie. No sickness. They usually only last a day. Is this troubling? Any explanations or recommendations? I would appreciate some insight.