Hi. The plaque and calculus accumulation in your lower teeth has lead to inflammation of gums and tooth bearing structures (periodontitis) over a period of time. Hence the redness, mild swelling, pain, detached gums etc.
For now start warm water salt rinses and chlorhexidine mouthwash twice a day and consult a dentist/periodontist soon without much delay.
Next Steps
See a dentist/periodontist soon
Health Tips
Advisable to see your dentist every 6 months.