My Dear
Welcome to Healthcaremagic!
Your details and symptoms have been carefully reviewed.
Please note the following points:
1 The problem seems to be related to a kind of abnormal response to the use of an
analgesic, antibiotic, or some other medication like
metronidazole.
2 If there is no such history, then an insect bite could be another possibility.
3 In any case, you will benefit by the use of a steroid-antibiotic combination applied locally twice daily after thorough cleaning with plain water pending final diagnosis.
4 You might like to wait for it to recede before seeking doctor opinion by visiting your physician personally. There is a good chance that it will settle.
You may skip investigations for now and can take anti allergic to reduce the severity of symptoms.
Wish you early recovery from Healthcaremagic!