Do you remember banging your lower 'calf' cris? If you did, it's obviously just a bruise which will disappear in time. If not, I would visit the nurse at your Doc's surgery to get it checked out.
I fell in the bath when I was scoofed a few years ago and landed on the tap with my thigh. It still has a lump even now and is uncomfy if I sit in a hard seat. The doc said it wasn't that unusual after a really hard knock but I would defo see the doc anyway.
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