If you are having difficulty breathing, if your mouth feels swollen and you are having a hard time swallowing, or if you are having an abnormal increase in heart rate, call 911. You could be going into anaphylactic shock.
Even if you aren't experiencing the above symptoms, you may want to see a doctor for prescription medications that help with swelling. Taking Benadryl will help, but if it's not enough, call your doctor.
Always, if you are ever in doubt, call your doctor.