How To Cure Bruise On Stomach At The Top Of Hip Bone?

My 3yo Toddler fell a few weeks ago and got a big ugly bruise on her stomach, right at about her hip bone. Shes super active and bruises are not unusual for her. Tonight we noticed (when she bumped it on something and cried that it hurt) that she still has a purple bruise in that spot, and it feels like a small, line-like lump is under the surface of it. Should we be worried? The bruise site sits just above the hip bone, actually on her abdomen.