Hi,
Sounds as though there might be a dental
pocket there. Plaque gets down between the tooth and the
gum and causes inflammation. The plaque needs to be removed daily.
Do you floss correctly? If not, that is probably the single most important thing you can do to help get that plaque out from the pocket area.
Try flossing at least once a day. I think it will help. Everything you mention sounds like plaque getting down into a pocket.