thanks for using health care magic.
It is most probable that you are having a hypersensitivity
reaction to an injected substance following the bite. This usually presents with intense itching and swelling of the affected area and may spread rapidly.
It is a good thing that you were put on antibiotics because another possible cause of your condition could be cellulitis
. However, it has to be broad spectrum antibiotic like a second generation cephalosporine together with metronidazole
You should consult your doctor for an evaluation and to prescribe antihistaminic drugs, corticosteroid etc as the case may be.
Best regards and hope this helps you.