Does Juvederm Volbella cause headaches? Or cause an allergic reaction that causes headaches?

Juvederm Volbella does not cause headaches.  The only reaction is localized swelling or bruising in the treated area.  Volbella is a great product to treat the fine lines around the mouth.  Please consult an expert in Volbella for the best cosmetic results.  Best, Dr. Green

Thank you for your question.  It's impossible to make an exact diagnosis without assessing you in-person.  That said, allergic reactions to Volbella and other hyaluronic acid fillers are exceptionally rare.  The rare patients who do experience allergic reactions to fillers typically have visible symptoms in the treated areas - in your case, we would expect to see persistent swelling, inflammation, and nodules in your lips.     
The symptoms you're describing sound more like a systemic illness.  I would recommend that you schedule an appointment with your primary care physician to discuss your symptoms, and to see if you are experiencing a viral or bacterial infection.  I hope you feel better soon!