I was stung by a plant

Patient: I live in the mountains of western North Carolina. I was walking with open toed shoes in a yard when it felt like I’d been stung by a bee. I found a small thorn stuck in my toe. I removed it the best I could and washed the area. This was on Sunday. This morning the toe woke me, itching horribly, swollen and throbbing. I’ve taken a benydrly. An idea what plant would sting like that and leave a lasting effect? How long will it last and when should I seek medical attention. Thanks!

Symptoms: Itching. Swollen. Throbbing.