(I am a 20 year old male with no serious medical history .) A heavy cart fell onto my arm a couple weeks ago. During the week after, I had a huge bruise on my inside forearm but then after it cleared up, two lumps appeared just under my skin . There s no pain and no discoloration. I m wondering if they were caused by the cart falling on me and/or if they are something threatening. Will they just go away with time?