since you already know that you have gingivitis
you must maintain good oral hygiene
gingivitis can be completely cured taking following measures by
brushing twice daily ( if possible after each meal),
using a mouthwash periodically,
if required getting scaling done periodically ,
gingivitis is mild and reversible condition but periodontitis
is alarming which causes pocket , pus,
(suppuration) and ultimately a bone damage . when the surrounding bone damages tooth becomes loose and falls off.
now coming to the lesion on your gum, this could be a simple gigival fibrosis
as you said you have no pain there but if there is associated pain or puss then that shows evidence of pocket there .
i would suggest you just do warm saline rinse for three to five days thrice daily . keep it under observation for five days, if you find any changes report the dentist
else needn't worry it will regress on its own,
remember you have to look for these changes in the lesion that is whether it is increasing in size , becoming painful, redness , swelling and bleeding etc then visit the dentist else need not worry
it will regress