Hello dear Please be calm I think you are having either plunger cusp or pocket. I suggest you to get an x ray for confirmation of diagnosis and best treatment For further details you can consult me Thanks

Hii...Sometimes if cap's margins are not proper, that can affect the adjacent teeth.. you have food lodgement in that area , that indicates there are high chances of cavity to produce. You should visit a dentist & Fill that gap before it went too deep. Pain is bcz of the food stuck in between your gums. Till then floss regularly & keep that area clean.

Clinical n radiological examination of that particular tooth will be helpful for proper diagnosis

Get xray of tooth.cause of pain has to be ruled out.if there is decay, get it filled. If there is gum recession, scaling and grafts can be done.you can consult through this for diagnosis and treatment plan.

Floss in between your teeth every day,so that food lodgement does not happen and cause gum and teeth problems.Rub dolo gel on your gums 2-3 times daily after brushing and flossing,so that damaged gums heals up.This treatment will help only if it's a gum issue.   If problem does not subside consult a dentist for an x-ray, they will diagnose the underlying problem and treat accordingly.