For About The Last 5 Days I've Had What Started

For about the last 5 days I've had what started as a spot on my right thigh as a spot that itched then a couple of days later I noticed a welt and any time it touched my pant leg or I touched it it just itched and now today there is a red line on my leg that raps around the thigh it itches and kinda feels like pins and needles