the bruising could be caused by your hormones i get them too. ive gained 12 or more pounds and i'm 5 1/2 months. my back has gotten so bad! i already have back problems (i have an extra vertabrae in my back, which hurts so bad in the first place). i couldn't imagine that pain being on my knees girl
My cousin turned out to have horrible pain in only one of her knees during pregnancy they kept fobbing her off saying it wAs cos carrying a baby anyway the pain stayed after birth n it turned out to be knee cancer, I don't wanna scare u or anything but if u go to the doctors dont let them fob u off
i would think the weight gain has a lot to do with it, but having gone through 2 knee surgeries i know what knee pain is and i completely get u!! it is horribleee and unbearable... as i said weight gain usually affects the knees, but i don't think it should cause bruising, if though u have a pinched nerve or maybe even tore ur meniscus (which u can do without knowing, I did.. twice) then that might be causing the bruising.. i would def go get it checked out, it is better to be safe than sorry. in the meanwhile aplly ice packs to them and elevate them. take tylenol to help with hte pain and swelling. and stay off of them as much as u can... hope u feel better! update when u know whats wrong!
This does not sound pregnancy related. While weight gain does put extra pressure on your knees especially and can cause pain this seems more than pregnancy related pain. Bruising could be a sign of anemia but it would usually occur in more than just your knee area. Maybe see your OB first than if needed they can refer you to a specialist.