random red hot sore spots in skin that turn bruise-like

about six months ago I thought I was getting bit by spiders.  Over the past six months at random times, every once in a while, I would get areas in my skin about an inch to two or three, that were red, sore, swollen, hot to touch, sometimes feel like hot liquid under the skin.  I am active and unload boxes and stuff so I thought I banged myself up and they were bruises.  the redness and sore subsides after a day or two and then it looks like a brown dark bruise then goes away.  I have had it on top of hands, ankles, mid front calf, upper thigh, stomach and I believe also around the eye socket.  Very painful to touch, feels sort of like a burn.  wonder if it is a traveling infection or blood disorder.  I did just have blood drawn to rule out somethings and maybe it will be diagnosed.  Any one else have this or know