First major injury

I had a bunch of errands to run yesterday morning so I left my kids in the capable hands of my husband. When I arrived home I was told a story that would horrify any mother. Casey was taking Emma to tumbling around the corner from our house. He put Cole in the umbrella stroller and let Emma push him. The way I understand it Emma was walking/running and hit a curb and Cole went flying. He hit his head pretty hard, Casey tells me. At this point I'm thinking, not my little baby boy. He's just so little and innocent. The goose egg on his head is pretty dramatic and it was time for a nap so of course I was worried about a concussion. I called my neighbor who informed me that forehead injuries swell more than other head bumps. Since Cole was happy and acting like his normal self I figured he was fine. I know I said this was his first major injury and maybe it wasn't such a huge injury but at the time I thought he might have a concussion. Emma is more cautious-type, she knows her limits, so I have yet to experience any major injuries as a parent. She skins her knees on a daily basis but I can count on one hand how many times she's needed a band-aid. Today the goose-egg looks a lot better and it's gone down quite a bit. Emma feels really bad about it. She kept telling Cole sorry yesterday. She also has been calling it an 'egg.' This morning she woke up and asked if Cole still had an 'egg' on his head.