Sorry, after 4 years I have no idea what you might do or if this could have been a horsefly bite or a wasp sting or just a thorn. I'd see a real doctor about this. We're not doctors here and can only tell you what our experiences are as patients.
When I get a bug bite I clean it and might use an antibiotic and a bandaid if there is an open wound. Antihistamine or ice is good for swelling, but after 4 years it's a bit late.