I woke up Sunday morning (after being at an outdoor wedding the night before) with a round purple bruise on the bottom of my foot. There is a red dot in the center of the bruise. It doesn't hurt but my foot looks a bit swollen now. I started feeling like I was getting a cold today as well (sneezing, achy, etc.). I'm sure it is a coincidence but wanted to mention it. Spider bite? Do you think I need to worry?