I had a little red welt with a white head on my knee a few days ago. I poped it like a zit and some puss came out. Not a lot but i thought nothing of it. The welt remained and a day or two later a red sweled line extended from it. Then the line doubled by the next day. Its about an inch long. The welt that i poped now has black on it and its a little sore. The skin around it dryed and peeled off a little. Im wondering if it could be just a bug bite or something thats not that big of a deal or something that could be serious and have it checked out. Thank you.