What is the size, location and colour of the swelling?
any associated discharge or difficulty in breathing?
did you consult a doctor yet?
when are you scheduled for doctor's appointments?
Thank you for the information,
As per the symptoms described by you it seems that you have developed the allergy to shot given which is causing such swelling, redness at the local site.
It is treated by the application of steroid pointment locally over the site.The commonly used steroids are dexamethasone, betasol, clobetasol, etc and you may use any one of them.The daily application 2-3times aday and the swelling will decrese.
You may also continue to take the benadryl which may ease the symptoms.If there is signs of infection then antibiotics may be needed though the chances are less.
Let me know if you have any doubt.
The low potency steroid ointments are available as OTC without prescription which you may get from near by pharmacy.