Thanks for your query
You may start doing warm compresses on the buttocks to help relieve the pain and the resolution of the bruise.You can also have oral pain killers containing Diclofenac
to reduce pain/swellin/discomfort. Try not having Ibuprofen
as they complicate bruises.
It is important you visit a physician to get yourself examined for a underlying soft tissue
and bony injury which might not be very evident now.
Hope this is helpful.TAKE CARE.