Hi thanks for your question.The lump which you developed following a bruise
is most probably a haematoma
(collection of blood under skin or in a muscle).Haematoma usually get resolved of itself,but if get infected can lead to puss formation.You can apply hot foamentation over the lump and heprin ointment over In case of pain you can take analgesic
anti inflammatory drugs(pain killer).Consultation with physician is encourged to rule out any infection in haematoma..
Hope this answers your question.