This happens because plaque and tartar build up along the gum line, causing gum inflammation (gingivitis/periodontal disease) which makes gums red, swollen, bleed easily and lose attachment to teeth & Left Untreated then this infection can lead to bone loss and loose teeth.
Next Steps
You need dental cleaning (scaling) to remove tartar and bacteria & improve daily brushing & flossing to reduce infection
Health Tips
Brush gently twice daily with a soft brush, floss daily if you have some time, avoid any harmful habits like smoking, chewing tobacco and don’t ignore bleeding, delaying treatment can make the condition worse