What Causes Red Circle Like Bruise Which Hurts?

i have a red circle on my leg, and its been here for a couple months now. i didnt think to pay any attention to it because it was very light at first and now is a little more red. it doesnt burn but it feels a little bit like if it is bruised but is not a bruise. around this area-skin is not as tight as this spot. as i rub my finger over it, it hurts. and if i push down it feels like a lump. i will make an appointment to the doctors but id like an idea of what it is first.