The most common localized bump after injury
is due to blood and fluid collection within the skin. This produces a bump with discolored skin above it sometimes without pain too. It will take around two to three weeks for such a swelling to come down.
So, if your friends bump is looking like one, try cold
compresses with ice pack and an antiflammatory drug like a dose of ibuprofen
twice a day after food for three days, until you get an appointment with the physician.
A physicians consultation is required to rule out any fracture
associated (detected by X-ray or CT Scan
)and the intervention needed accordingly. You might need an antibiotic too (as precautionary measure)as hematomas are prone for infections.
But confirm it with your doctor.