For the past few days, I've had an itchy spot on my right leg. There was nothing visible, and I tried not to scratch it much. Now yesterday, the area is a red splotch about 3/4 of an inch in diameter. I know this can't be something like a mosquito bite since none in the past have looked like this. I wear long pants all the time, so there's no way I know of that it could be poison ivy. I took a picture of it, but can't post it here since there's no way of posting attachments. I hope my description is good enough.

Any idea what this could be? Is it worth seeing a doctor for?