I noticed I got bitten by something below the side of my knee, may be a mosquito bite or fly bite. I didn't pay much mind to it... a few hours later I had a huge bruise! The upper part of the bruise had a round skin colored circle, and around it was bluish black with weird purple dots scattered. I went to my doctor 4 or 5 days later and she claimed it was nothing. I STILL have this bruise. The purple dots have turned into purple streaks. I just want to know what it is, what could've bitten me, and if it could be dangerous...?