I Have Had An Unidentified Bug Bite O The Bottom

I have had an unidentified bug bite o the bottom side of my left hand wrist for about 5 days now. It has gotten bigger and is kind of painful to the touch and so is the area around it, now ive noticed this soreness in my left arm and a red line running from the bite to mid way of my bicep, i had just lifted a few hours ago but am still concerned.