I have what I think may be a group of spider bites- 6 or 7 of them in close range - above my knee on the outer side of my leg. I have had them for several days. It feels as though the top layers of my leg are kinda numb. What is the level of seriousness of this? Secondarily, tonight I discovered multiple bites behind my knee on the same leg. I'm a bit puzzled as I don't remember getting bitten and it doesn't look like a mosquito bite.