the lump has appeared due to toothbrush injury
apply dologel/mucopain gel on the affected site.avoid harsh brushing methods.
use soft-bristled toothbrush to clean your teeth.
always hold your toothbrush in 45 degree angle,and brush in upper arch from top to bottom and in lower arch from bottom to top.
do not apply too much of pressure on tooth while brushing,as it can cause abrasion and attrition of teeth.
visit a dentist
and get your teeth cleaned to remove plaque
deposits as it can lead to gingivitis
take cap.spamox-500mg,thrice daily for 3 days,to subside the infection occurred.