You need to put ice to your swollen lips so that for the time being you will get rid of these steroids. The use of anti-biotic can help you to get rid of burning and swollen lips.
What's The Treatment For Swollen Lips Due To Reaction To Steroids Administered In An IV?
Sounds like you are having an allergic reaction. Give your body time to rid itself of the steroids. Your lips should return to normal within 24 hours. If not, then call your dentist and tell him what's going on.