Schedule a follow up with your injector to discuss the pain you are feeling. Your injector will be the best person to assess your pain, as they know exactly where they injected you.
An allergic reaction is extremely rare with hyaluronic acid. You may want to consider the reaction was to the lidocaine in the product; which is also rare. Follow up with your family Dr.
All the Best.
Where was the Juvederm injected? It is very rare for people to experience allergic reactions to Juvederm so I'm more inclined to think it was a coincidence. I would have a medical check up with your doctor to determine the cause.
It is VERY rare to have a reaction or allergy to Juvederm because it is a hyaluronic acid, which naturally occurs in the body. It could be mere coincidence that these two things occurred. Also, you didn't state where your filler was injected. Was it put into the jaw or near the eyes? The one and only time I saw a reaction to Juvederm, in a journal, not in person, the patient also had swelling and redness where the filler was injected. To have a true allergy, you'd have to have irritation at the site, and not just the other things you listed. Nevertheless, be seen by a doctor to determine what's going on. Even if it is unrelated, you should still be treating your illness.
"This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."
It is unusual to have an allergy reaction to Juvederm. Your symptoms may or may not be related to the treatment, and I would recommend you see your physician for a thorough exam. You did not state where your Juvederm was injected so it is hard to say how the symptoms could be related, but either way I would get this checked out.