Hello and hope you are doing well.
It could be an allergic reaction to the medication, but I would suggest you obtain a referral to an allergist or an ENT who does allergy testing. That is the only way to reliably know what is causing your allergic reaction. Some allergies can be life-threatening as they can precipitate anaphylactic shock in which the swelling can be so severe that it impairs the ability to breathe. Therefore, I would suggest you see someone as soon as possible.
Hope this helped and do keep us posted.