Dear user, A soft lump, after an injury with skin bruise on it is most likely a small collection of blood under the skin, Hematoma, unless there was already a Lipoma (a lumpy collection of fat under the skin) there, which became more obvious after the trauma which is less likely (given the fact that you didn t mention its presence before) If it is not increasing in size or the skin is not damaged, you could give her some anti-inflammatory (neurofen) and cold packs and it should settle down in few days, as blood absorbs. In case the lump persists even after the discoloration is settled, you can get it checked for the presence of skin cyst or lipoma. It is always advisable to take her to doctor regardless of the lump, to get her ribs examined, esp if she is in loads of pain. Hope it answered your query, do write back if anything else. Goodluck