Does not appear as an infection. More as a reaction that needs more steroid therapy. Plus STOP everything else going into your lips!
You may be having a delayed allergic reaction to the Juvederm. Allergy to hyaluroindase is rare, however your doctor can put a little bit into your forearm and then watch for any swelling or redness which would indicate an allergy to this. If no problems, you should have injection into your lips to eliminate the juvederm. Improvement with the Medrol indicates that it is some sort of inflammatory or allergy as opposed to infection.