I Have Bruising And Pain Along With Very Swollen Veins

I have bruising and pain along with very swollen veins on my left outer knee. I am 43, male, nonsmoker, in fairly good shape. I did take a good hit to this area at work, but did not think it hard enough to even bruise. I have had thrombus veins in my legs before,but not like this. Pain is intensified when standing. Been about 3 weeks.